diff --git a/.eslintrc.js b/.eslintrc.js
index ed1509d3f..34e935ece 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -44,6 +44,7 @@ module.exports = {
     // Problems with optional parameters
     '@typescript-eslint/no-unnecessary-condition': 'off',
     '@typescript-eslint/prefer-optional-chain': 'error',
+    '@typescript-eslint/promise-function-async': [ 'error', { checkArrowFunctions: false } ],
     '@typescript-eslint/space-before-function-paren': [ 'error', 'never' ],
     '@typescript-eslint/unbound-method': 'off',
     '@typescript-eslint/unified-signatures': 'off',
diff --git a/.github/ISSUE_TEMPLATE/bug-report.md b/.github/ISSUE_TEMPLATE/bug-report.md
new file mode 100644
index 000000000..34415882a
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/bug-report.md
@@ -0,0 +1,16 @@
+---
+name: "\U0001F41B Bug report"
+about: If something is not working as expected or crashes
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+#### Environment
+- Server version: *Output of `community-solid-server --version` for a global or `npx community-solid-server --version` for a local installation*
+- Node.js version: *Output of `node -v`*
+- npm version: *Output of `npm -v`*
+
+#### Description
+<!-- Please describe the exact problem as clearly as possible. Provide any error messages thrown. -->
diff --git a/.github/ISSUE_TEMPLATE/feature-request.md b/.github/ISSUE_TEMPLATE/feature-request.md
new file mode 100644
index 000000000..fca4c3fec
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/feature-request.md
@@ -0,0 +1,13 @@
+---
+name: "➕ Feature request"
+about: Suggest an idea for this project
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+#### Feature description:
+
+<!--In case you want to start a discussion about an idea, discussions are better suited for this https://github.com/solid/community-server/discussions -->
+<!--A clear and concise description of what you want to happen.-->
diff --git a/.github/ISSUE_TEMPLATE/question.md b/.github/ISSUE_TEMPLATE/question.md
new file mode 100644
index 000000000..7add40a8a
--- /dev/null
+++ b/.github/ISSUE_TEMPLATE/question.md
@@ -0,0 +1,13 @@
+---
+name: "❓ Question"
+about: A general question
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+#### Question
+
+<!-- Questions are usually better suited for discussions, which can be found at https://github.com/solid/community-server/discussions -->
+<!-- In case you think this would better as an issue, please provide a clear and concisely formulated question.-->
diff --git a/.github/PULL_REQUEST_TEMPLATE.md b/.github/PULL_REQUEST_TEMPLATE.md
new file mode 100644
index 000000000..7ef89572c
--- /dev/null
+++ b/.github/PULL_REQUEST_TEMPLATE.md
@@ -0,0 +1,15 @@
+<!-- 
+Things to check before submitting a pull request:
+  * Label this PR with the correct semver label (if you have permission to do so).
+    - semver.patch: Backwards compatible bug fixes.
+    - semver.minor: Backwards compatible feature additions.
+    - semver.major: Breaking changes. This includes changing interfaces or configuration behaviour.
+  * Target the correct branch. Patch updates can target main, other changes should target the latest versions/* branch.
+  * Update the RELEASE_NOTES.md document in case of relevant feature or config changes.
+-->
+
+#### Related issues
+<!-- Reference any relevant issues here. Closing keywords only have an effect when targeting the main branch. -->
+
+#### Description
+<!-- Describe the relevant changes in this PR. Also add notes that might be relevant for code reviewers. -->
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 1e7bae486..921d7ac1a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -46,7 +46,6 @@ jobs:
           - '14.x'
           - '16.0'
           - '16.x'
-          - '17.0'
           - '17.x'
     timeout-minutes: 10
     steps:
@@ -74,11 +73,9 @@ jobs:
         run: npm run test:deploy
 
   test-integration:
-    runs-on: ${{ matrix.operating-system }}
+    runs-on: ubuntu-latest
     strategy:
       matrix:
-        operating-system:
-          - ubuntu-latest
         node-version:
           - '12.x'
           - '14.x'
@@ -109,6 +106,29 @@ jobs:
       - name: Run integration tests
         run: npm run test:integration
 
+  test-integration-windows:
+    runs-on: windows-latest
+    strategy:
+      matrix:
+        node-version:
+          - '12.x'
+          - '14.x'
+          - '16.x'
+    timeout-minutes: 10
+    steps:
+      - name: Use Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v2
+        with:
+          node-version: ${{ matrix.node-version }}
+      - name: Ensure line endings are consistent
+        run: git config --global core.autocrlf input
+      - name: Check out repository
+        uses: actions/checkout@v2
+      - name: Install dependencies and run build scripts
+        run: npm ci
+      - name: Run integration tests
+        run: npm run test:integration
+
   coveralls:
     needs: test-unit
     runs-on: ubuntu-latest
diff --git a/.github/workflows/schedule.yml b/.github/workflows/schedule.yml
index b61d7a04b..42060327e 100644
--- a/.github/workflows/schedule.yml
+++ b/.github/workflows/schedule.yml
@@ -14,7 +14,7 @@ jobs:
       matrix:
         branch:
           - 'main'
-          - 'versions/2.1.0'
+          - 'versions/3.0.0'
     timeout-minutes: 10
     steps:
       - name: Use Node.js 16.x
diff --git a/package-lock.json b/package-lock.json
index 307c415cc..14c2c49a9 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -30,7 +30,7 @@
         "@types/sparqljs": "^3.1.2",
         "@types/url-join": "^4.0.0",
         "@types/uuid": "^8.3.0",
-        "@types/ws": "^7.4.5",
+        "@types/ws": "^8.2.0",
         "@types/yargs": "^17.0.0",
         "arrayify-stream": "^1.0.0",
         "async-lock": "^1.3.0",
@@ -56,13 +56,13 @@
         "rdf-serialize": "^1.1.0",
         "redis": "^3.1.2",
         "redlock": "^4.2.0",
-        "sparqlalgebrajs": "^3.0.0",
+        "sparqlalgebrajs": "^4.0.1",
         "sparqljs": "^3.4.2",
         "url-join": "^4.0.1",
         "uuid": "^8.3.2",
         "winston": "^3.3.3",
         "winston-transport": "^4.4.0",
-        "ws": "^8.0.0",
+        "ws": "^8.2.3",
         "yargs": "^17.0.1"
       },
       "bin": {
@@ -3780,6 +3780,24 @@
         "sparqlalgebrajs": "^3.0.1"
       }
     },
+    "node_modules/@comunica/types/node_modules/sparqlalgebrajs": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-3.0.3.tgz",
+      "integrity": "sha512-XFNhsO55bprayrM35h/jY0kzzuGc3oZ1On3kc+s7Un0BFQBXa046aLcMZFp4MYSvn7GtMe9eZ08ONFnBH5kEsQ==",
+      "dependencies": {
+        "@rdfjs/types": "*",
+        "@types/sparqljs": "^3.1.2",
+        "fast-deep-equal": "^3.1.3",
+        "minimist": "^1.2.5",
+        "rdf-data-factory": "^1.1.0",
+        "rdf-isomorphic": "^1.3.0",
+        "rdf-string": "^1.6.0",
+        "sparqljs": "^3.4.2"
+      },
+      "bin": {
+        "sparqlalgebrajs": "bin/sparqlalgebrajs.js"
+      }
+    },
     "node_modules/@comunica/utils-datasource": {
       "version": "1.21.1",
       "resolved": "https://registry.npmjs.org/@comunica/utils-datasource/-/utils-datasource-1.21.1.tgz",
@@ -4886,9 +4904,9 @@
       "integrity": "sha512-82E/lVRaqelV9qmRzzJ1PKTpyrpnT7mwdneKNJB9hUtypZDMggloDfFUCIqRRx3lYRxteCwXSq9c+W71Vf0QnQ=="
     },
     "node_modules/@types/sparqljs": {
-      "version": "3.1.2",
-      "resolved": "https://registry.npmjs.org/@types/sparqljs/-/sparqljs-3.1.2.tgz",
-      "integrity": "sha512-tLfrnBuK37P2Bn8Fo7Qik95sBXYHw5D+gq3MMq1HVyoTpCWivwPnP0Mmd7Apamdc9eH3mLJwIZIETHCQ6HxMUw==",
+      "version": "3.1.3",
+      "resolved": "https://registry.npmjs.org/@types/sparqljs/-/sparqljs-3.1.3.tgz",
+      "integrity": "sha512-nmFgmR6ns4i8sg9fYu+293H+PMLKmDOZy34sgwgAeUEEiIqSs4guj5aCZRt3gq1g0yuKXkqrxLDq/684g7pGtQ==",
       "dependencies": {
         "rdf-js": "^4.0.2"
       }
@@ -4934,9 +4952,9 @@
       "integrity": "sha512-eQ9qFW/fhfGJF8WKHGEHZEyVWfZxrT+6CLIJGBcZPfxUh/+BnEj+UCGYMlr9qZuX/2AltsvwrGqp0LhEW8D0zQ=="
     },
     "node_modules/@types/ws": {
-      "version": "7.4.5",
-      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-7.4.5.tgz",
-      "integrity": "sha512-8mbDgtc8xpxDDem5Gwj76stBDJX35KQ3YBoayxlqUQcL5BZUthiqP/VQ4PQnLHqM4PmlbyO74t98eJpURO+gPA==",
+      "version": "8.2.0",
+      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-8.2.0.tgz",
+      "integrity": "sha512-cyeefcUCgJlEk+hk2h3N+MqKKsPViQgF5boi9TTHSK+PoR9KWBb/C5ccPcDyAqgsbAYHTwulch725DV84+pSpg==",
       "dependencies": {
         "@types/node": "*"
       }
@@ -14164,18 +14182,18 @@
       "integrity": "sha512-0tF3AGSD1ppQeuffsLDIOWlKUd3lS92tFxcsrh5Pe3ZphhnoK+oXIBTzOAThZCiuINZLvpiLH/1VS1/ANEJVig=="
     },
     "node_modules/sparqlalgebrajs": {
-      "version": "3.0.3",
-      "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-3.0.3.tgz",
-      "integrity": "sha512-XFNhsO55bprayrM35h/jY0kzzuGc3oZ1On3kc+s7Un0BFQBXa046aLcMZFp4MYSvn7GtMe9eZ08ONFnBH5kEsQ==",
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-4.0.1.tgz",
+      "integrity": "sha512-/YOn4+5JEawI29h9eFYb9rScCtiLIK4TG+MrXpbJlHDjL8W34+V/RQoXqeau4SFXtA60Vzc7LRokefguh+I37Q==",
       "dependencies": {
         "@rdfjs/types": "*",
-        "@types/sparqljs": "^3.1.2",
+        "@types/sparqljs": "^3.1.3",
         "fast-deep-equal": "^3.1.3",
         "minimist": "^1.2.5",
         "rdf-data-factory": "^1.1.0",
         "rdf-isomorphic": "^1.3.0",
         "rdf-string": "^1.6.0",
-        "sparqljs": "^3.4.2"
+        "sparqljs": "^3.5.1"
       },
       "bin": {
         "sparqlalgebrajs": "bin/sparqlalgebrajs.js"
@@ -14220,9 +14238,9 @@
       }
     },
     "node_modules/sparqljs": {
-      "version": "3.4.2",
-      "resolved": "https://registry.npmjs.org/sparqljs/-/sparqljs-3.4.2.tgz",
-      "integrity": "sha512-MmmZ6cMuvhf4Eh2FXX21dalgADUiZ9WN8XKMedwhTFg0r7W09/o8wvoZ8C4yA6FptnjjAjm+mGnxAEpkSRY3QQ==",
+      "version": "3.5.1",
+      "resolved": "https://registry.npmjs.org/sparqljs/-/sparqljs-3.5.1.tgz",
+      "integrity": "sha512-sHc6z7hNF3ACvXurKe8hT1sD52Fc0fN3uPLS6SQnXRV9CJl33GNAS4w5Dd3X3GgykUt9SlnjhI1QRKhLzun4qQ==",
       "dependencies": {
         "rdf-data-factory": "^1.0.4"
       },
@@ -15577,9 +15595,9 @@
       }
     },
     "node_modules/ws": {
-      "version": "8.0.0",
-      "resolved": "https://registry.npmjs.org/ws/-/ws-8.0.0.tgz",
-      "integrity": "sha512-6AcSIXpBlS0QvCVKk+3cWnWElLsA6SzC0lkQ43ciEglgXJXiCWK3/CGFEJ+Ybgp006CMibamAsqOlxE9s4AvYA==",
+      "version": "8.2.3",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.2.3.tgz",
+      "integrity": "sha512-wBuoj1BDpC6ZQ1B7DWQBYVLphPWkm8i9Y0/3YdHjHKHiohOJ1ws+3OccDWtH+PoC9DZD5WOTrJvNbWvjS6JWaA==",
       "engines": {
         "node": ">=10.0.0"
       },
@@ -18574,6 +18592,23 @@
         "asynciterator": "^3.2.0",
         "immutable": "^3.8.2",
         "sparqlalgebrajs": "^3.0.1"
+      },
+      "dependencies": {
+        "sparqlalgebrajs": {
+          "version": "3.0.3",
+          "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-3.0.3.tgz",
+          "integrity": "sha512-XFNhsO55bprayrM35h/jY0kzzuGc3oZ1On3kc+s7Un0BFQBXa046aLcMZFp4MYSvn7GtMe9eZ08ONFnBH5kEsQ==",
+          "requires": {
+            "@rdfjs/types": "*",
+            "@types/sparqljs": "^3.1.2",
+            "fast-deep-equal": "^3.1.3",
+            "minimist": "^1.2.5",
+            "rdf-data-factory": "^1.1.0",
+            "rdf-isomorphic": "^1.3.0",
+            "rdf-string": "^1.6.0",
+            "sparqljs": "^3.4.2"
+          }
+        }
       }
     },
     "@comunica/utils-datasource": {
@@ -19578,9 +19613,9 @@
       "integrity": "sha512-82E/lVRaqelV9qmRzzJ1PKTpyrpnT7mwdneKNJB9hUtypZDMggloDfFUCIqRRx3lYRxteCwXSq9c+W71Vf0QnQ=="
     },
     "@types/sparqljs": {
-      "version": "3.1.2",
-      "resolved": "https://registry.npmjs.org/@types/sparqljs/-/sparqljs-3.1.2.tgz",
-      "integrity": "sha512-tLfrnBuK37P2Bn8Fo7Qik95sBXYHw5D+gq3MMq1HVyoTpCWivwPnP0Mmd7Apamdc9eH3mLJwIZIETHCQ6HxMUw==",
+      "version": "3.1.3",
+      "resolved": "https://registry.npmjs.org/@types/sparqljs/-/sparqljs-3.1.3.tgz",
+      "integrity": "sha512-nmFgmR6ns4i8sg9fYu+293H+PMLKmDOZy34sgwgAeUEEiIqSs4guj5aCZRt3gq1g0yuKXkqrxLDq/684g7pGtQ==",
       "requires": {
         "rdf-js": "^4.0.2"
       }
@@ -19626,9 +19661,9 @@
       "integrity": "sha512-eQ9qFW/fhfGJF8WKHGEHZEyVWfZxrT+6CLIJGBcZPfxUh/+BnEj+UCGYMlr9qZuX/2AltsvwrGqp0LhEW8D0zQ=="
     },
     "@types/ws": {
-      "version": "7.4.5",
-      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-7.4.5.tgz",
-      "integrity": "sha512-8mbDgtc8xpxDDem5Gwj76stBDJX35KQ3YBoayxlqUQcL5BZUthiqP/VQ4PQnLHqM4PmlbyO74t98eJpURO+gPA==",
+      "version": "8.2.0",
+      "resolved": "https://registry.npmjs.org/@types/ws/-/ws-8.2.0.tgz",
+      "integrity": "sha512-cyeefcUCgJlEk+hk2h3N+MqKKsPViQgF5boi9TTHSK+PoR9KWBb/C5ccPcDyAqgsbAYHTwulch725DV84+pSpg==",
       "requires": {
         "@types/node": "*"
       }
@@ -26661,18 +26696,18 @@
       "integrity": "sha512-0tF3AGSD1ppQeuffsLDIOWlKUd3lS92tFxcsrh5Pe3ZphhnoK+oXIBTzOAThZCiuINZLvpiLH/1VS1/ANEJVig=="
     },
     "sparqlalgebrajs": {
-      "version": "3.0.3",
-      "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-3.0.3.tgz",
-      "integrity": "sha512-XFNhsO55bprayrM35h/jY0kzzuGc3oZ1On3kc+s7Un0BFQBXa046aLcMZFp4MYSvn7GtMe9eZ08ONFnBH5kEsQ==",
+      "version": "4.0.1",
+      "resolved": "https://registry.npmjs.org/sparqlalgebrajs/-/sparqlalgebrajs-4.0.1.tgz",
+      "integrity": "sha512-/YOn4+5JEawI29h9eFYb9rScCtiLIK4TG+MrXpbJlHDjL8W34+V/RQoXqeau4SFXtA60Vzc7LRokefguh+I37Q==",
       "requires": {
         "@rdfjs/types": "*",
-        "@types/sparqljs": "^3.1.2",
+        "@types/sparqljs": "^3.1.3",
         "fast-deep-equal": "^3.1.3",
         "minimist": "^1.2.5",
         "rdf-data-factory": "^1.1.0",
         "rdf-isomorphic": "^1.3.0",
         "rdf-string": "^1.6.0",
-        "sparqljs": "^3.4.2"
+        "sparqljs": "^3.5.1"
       }
     },
     "sparqlee": {
@@ -26710,9 +26745,9 @@
       }
     },
     "sparqljs": {
-      "version": "3.4.2",
-      "resolved": "https://registry.npmjs.org/sparqljs/-/sparqljs-3.4.2.tgz",
-      "integrity": "sha512-MmmZ6cMuvhf4Eh2FXX21dalgADUiZ9WN8XKMedwhTFg0r7W09/o8wvoZ8C4yA6FptnjjAjm+mGnxAEpkSRY3QQ==",
+      "version": "3.5.1",
+      "resolved": "https://registry.npmjs.org/sparqljs/-/sparqljs-3.5.1.tgz",
+      "integrity": "sha512-sHc6z7hNF3ACvXurKe8hT1sD52Fc0fN3uPLS6SQnXRV9CJl33GNAS4w5Dd3X3GgykUt9SlnjhI1QRKhLzun4qQ==",
       "requires": {
         "rdf-data-factory": "^1.0.4"
       }
@@ -27816,9 +27851,9 @@
       }
     },
     "ws": {
-      "version": "8.0.0",
-      "resolved": "https://registry.npmjs.org/ws/-/ws-8.0.0.tgz",
-      "integrity": "sha512-6AcSIXpBlS0QvCVKk+3cWnWElLsA6SzC0lkQ43ciEglgXJXiCWK3/CGFEJ+Ybgp006CMibamAsqOlxE9s4AvYA==",
+      "version": "8.2.3",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.2.3.tgz",
+      "integrity": "sha512-wBuoj1BDpC6ZQ1B7DWQBYVLphPWkm8i9Y0/3YdHjHKHiohOJ1ws+3OccDWtH+PoC9DZD5WOTrJvNbWvjS6JWaA==",
       "requires": {}
     },
     "xdg-basedir": {
diff --git a/package.json b/package.json
index 0b2684840..4580f267b 100644
--- a/package.json
+++ b/package.json
@@ -96,7 +96,7 @@
     "@types/sparqljs": "^3.1.2",
     "@types/url-join": "^4.0.0",
     "@types/uuid": "^8.3.0",
-    "@types/ws": "^7.4.5",
+    "@types/ws": "^8.2.0",
     "@types/yargs": "^17.0.0",
     "arrayify-stream": "^1.0.0",
     "async-lock": "^1.3.0",
@@ -122,13 +122,13 @@
     "rdf-serialize": "^1.1.0",
     "redis": "^3.1.2",
     "redlock": "^4.2.0",
-    "sparqlalgebrajs": "^3.0.0",
+    "sparqlalgebrajs": "^4.0.1",
     "sparqljs": "^3.4.2",
     "url-join": "^4.0.1",
     "uuid": "^8.3.2",
     "winston": "^3.3.3",
     "winston-transport": "^4.4.0",
-    "ws": "^8.0.0",
+    "ws": "^8.2.3",
     "yargs": "^17.0.1"
   },
   "devDependencies": {
diff --git a/src/authorization/permissions/SparqlPatchModesExtractor.ts b/src/authorization/permissions/SparqlPatchModesExtractor.ts
index cad78bc52..cae2798d6 100644
--- a/src/authorization/permissions/SparqlPatchModesExtractor.ts
+++ b/src/authorization/permissions/SparqlPatchModesExtractor.ts
@@ -40,25 +40,25 @@ export class SparqlPatchModesExtractor extends ModesExtractor {
     return Boolean((data as SparqlUpdatePatch).algebra);
   }
 
-  private isSupported(op: Algebra.Operation): boolean {
+  private isSupported(op: Algebra.Update): boolean {
     if (this.isDeleteInsert(op) || this.isNop(op)) {
       return true;
     }
     if (op.type === Algebra.types.COMPOSITE_UPDATE) {
-      return (op as Algebra.CompositeUpdate).updates.every((update): boolean => this.isSupported(update));
+      return op.updates.every((update): boolean => this.isSupported(update));
     }
     return false;
   }
 
-  private isDeleteInsert(op: Algebra.Operation): op is Algebra.DeleteInsert {
+  private isDeleteInsert(op: Algebra.Update): op is Algebra.DeleteInsert {
     return op.type === Algebra.types.DELETE_INSERT;
   }
 
-  private isNop(op: Algebra.Operation): op is Algebra.Nop {
+  private isNop(op: Algebra.Update): op is Algebra.Nop {
     return op.type === Algebra.types.NOP;
   }
 
-  private needsAppend(update: Algebra.Operation): boolean {
+  private needsAppend(update: Algebra.Update): boolean {
     if (this.isNop(update)) {
       return false;
     }
@@ -69,7 +69,7 @@ export class SparqlPatchModesExtractor extends ModesExtractor {
     return (update as Algebra.CompositeUpdate).updates.some((op): boolean => this.needsAppend(op));
   }
 
-  private needsWrite(update: Algebra.Operation): boolean {
+  private needsWrite(update: Algebra.Update): boolean {
     if (this.isNop(update)) {
       return false;
     }
diff --git a/src/http/UnsecureWebSocketsProtocol.ts b/src/http/UnsecureWebSocketsProtocol.ts
index 5bfe5040b..bafc520c3 100644
--- a/src/http/UnsecureWebSocketsProtocol.ts
+++ b/src/http/UnsecureWebSocketsProtocol.ts
@@ -1,5 +1,5 @@
 import { EventEmitter } from 'events';
-import type WebSocket from 'ws';
+import type { WebSocket } from 'ws';
 import { getLoggerFor } from '../logging/LogUtil';
 import type { HttpRequest } from '../server/HttpRequest';
 import { WebSocketHandler } from '../server/WebSocketHandler';
diff --git a/src/http/input/body/SparqlUpdateBodyParser.ts b/src/http/input/body/SparqlUpdateBodyParser.ts
index b9600769a..8b0d871e8 100644
--- a/src/http/input/body/SparqlUpdateBodyParser.ts
+++ b/src/http/input/body/SparqlUpdateBodyParser.ts
@@ -26,7 +26,7 @@ export class SparqlUpdateBodyParser extends BodyParser {
     const sparql = await readableToString(request);
     let algebra: Algebra.Operation;
     try {
-      algebra = translate(sparql, { quads: true, baseIRI: metadata.identifier.value });
+      algebra = translate(sparql, { quads: true, baseIRI: metadata.identifier.value }) as Algebra.Update;
     } catch (error: unknown) {
       this.logger.warn('Could not translate SPARQL query to SPARQL algebra', { error });
       throw new BadRequestHttpError(createErrorMessage(error), { cause: error });
diff --git a/src/http/output/error/ConvertingErrorHandler.ts b/src/http/output/error/ConvertingErrorHandler.ts
index 278c7e45b..7bd6faecd 100644
--- a/src/http/output/error/ConvertingErrorHandler.ts
+++ b/src/http/output/error/ConvertingErrorHandler.ts
@@ -3,7 +3,7 @@ import type {
   RepresentationConverterArgs,
 } from '../../../storage/conversion/RepresentationConverter';
 import { INTERNAL_ERROR } from '../../../util/ContentTypes';
-import { getStatusCode } from '../../../util/errors/ErrorUtil';
+import { getStatusCode } from '../../../util/errors/HttpErrorUtil';
 import { toLiteral } from '../../../util/TermUtil';
 import { HTTP, XSD } from '../../../util/Vocabularies';
 import { BasicRepresentation } from '../../representation/BasicRepresentation';
diff --git a/src/http/output/error/SafeErrorHandler.ts b/src/http/output/error/SafeErrorHandler.ts
index 7071c773d..9da9b095d 100644
--- a/src/http/output/error/SafeErrorHandler.ts
+++ b/src/http/output/error/SafeErrorHandler.ts
@@ -1,5 +1,6 @@
 import { getLoggerFor } from '../../../logging/LogUtil';
-import { createErrorMessage, getStatusCode } from '../../../util/errors/ErrorUtil';
+import { createErrorMessage } from '../../../util/errors/ErrorUtil';
+import { getStatusCode } from '../../../util/errors/HttpErrorUtil';
 import { guardedStreamFrom } from '../../../util/StreamUtil';
 import { toLiteral } from '../../../util/TermUtil';
 import { HTTP, XSD } from '../../../util/Vocabularies';
diff --git a/src/index.ts b/src/index.ts
index 5352a0bf6..fd5342005 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -320,6 +320,7 @@ export * from './util/errors/ConflictHttpError';
 export * from './util/errors/ErrorUtil';
 export * from './util/errors/ForbiddenHttpError';
 export * from './util/errors/HttpError';
+export * from './util/errors/HttpErrorUtil';
 export * from './util/errors/InternalServerError';
 export * from './util/errors/MethodNotAllowedHttpError';
 export * from './util/errors/NotFoundHttpError';
diff --git a/src/server/WebSocketHandler.ts b/src/server/WebSocketHandler.ts
index ec7c40f5a..d968edabb 100644
--- a/src/server/WebSocketHandler.ts
+++ b/src/server/WebSocketHandler.ts
@@ -1,4 +1,4 @@
-import type WebSocket from 'ws';
+import type { WebSocket } from 'ws';
 import { AsyncHandler } from '../util/handlers/AsyncHandler';
 import type { HttpRequest } from './HttpRequest';
 
diff --git a/src/server/WebSocketServerFactory.ts b/src/server/WebSocketServerFactory.ts
index a154ff4cc..5826e1501 100644
--- a/src/server/WebSocketServerFactory.ts
+++ b/src/server/WebSocketServerFactory.ts
@@ -1,6 +1,6 @@
 import type { Server } from 'http';
 import type { Socket } from 'net';
-import type WebSocket from 'ws';
+import type { WebSocket } from 'ws';
 import { Server as WebSocketServer } from 'ws';
 import type { HttpRequest } from './HttpRequest';
 import type { HttpServerFactory } from './HttpServerFactory';
diff --git a/src/util/PromiseUtil.ts b/src/util/PromiseUtil.ts
index 7b72f82ee..8d38b3ae9 100644
--- a/src/util/PromiseUtil.ts
+++ b/src/util/PromiseUtil.ts
@@ -1,5 +1,7 @@
+import { createAggregateError } from './errors/HttpErrorUtil';
+
 // eslint-disable-next-line @typescript-eslint/no-empty-function
-const infinitePromise = new Promise<boolean>((): void => {});
+function noop(): void {}
 
 /**
  * A function that simulates the Array.some behaviour but on an array of Promises.
@@ -14,17 +16,36 @@ const infinitePromise = new Promise<boolean>((): void => {});
  * 2. throwing an error should be logically equivalent to returning false.
  */
 export async function promiseSome(predicates: Promise<boolean>[]): Promise<boolean> {
-  // These promises will only finish when their predicate returns true
-  const infinitePredicates = predicates.map(async(predicate): Promise<boolean> => predicate.then(
-    async(value): Promise<boolean> => value ? true : infinitePromise,
-    async(): Promise<boolean> => infinitePromise,
-  ));
-
-  // Returns after all predicates are resolved
-  const finalPromise = Promise.allSettled(predicates).then((results): boolean =>
-    results.some((result): boolean => result.status === 'fulfilled' && result.value));
-
-  // Either one of the infinitePredicates will return true,
-  // or finalPromise will return the result if none of them did or finalPromise was faster
-  return Promise.race([ ...infinitePredicates, finalPromise ]);
+  return new Promise((resolve): void => {
+    function resolveIfTrue(value: boolean): void {
+      if (value) {
+        resolve(true);
+      }
+    }
+    Promise.all(predicates.map((predicate): Promise<void> => predicate.then(resolveIfTrue, noop)))
+      .then((): void => resolve(false), noop);
+  });
+}
+
+/**
+ * Obtains the values of all fulfilled promises.
+ * If there are rejections (and `ignoreErrors` is false), throws a combined error of all rejected promises.
+ */
+export async function allFulfilled<T>(promises: Promise<T> [], ignoreErrors = false): Promise<T[]> {
+  // Collect values and errors
+  const values: T[] = [];
+  const errors: Error[] = [];
+  for (const result of await Promise.allSettled(promises)) {
+    if (result.status === 'fulfilled') {
+      values.push(result.value);
+    } else if (!ignoreErrors) {
+      errors.push(result.reason);
+    }
+  }
+
+  // Either throw or return
+  if (errors.length > 0) {
+    throw createAggregateError(errors);
+  }
+  return values;
 }
diff --git a/src/util/errors/ErrorUtil.ts b/src/util/errors/ErrorUtil.ts
index 84e94716e..405b29c80 100644
--- a/src/util/errors/ErrorUtil.ts
+++ b/src/util/errors/ErrorUtil.ts
@@ -1,5 +1,4 @@
 import { types } from 'util';
-import { HttpError } from './HttpError';
 
 /**
  * Checks if the input is an {@link Error}.
@@ -25,10 +24,3 @@ export function assertError(error: unknown): asserts error is Error {
 export function createErrorMessage(error: unknown): string {
   return isError(error) ? error.message : `Unknown error: ${error}`;
 }
-
-/**
- * Returns the HTTP status code corresponding to the error.
- */
-export function getStatusCode(error: Error): number {
-  return HttpError.isInstance(error) ? error.statusCode : 500;
-}
diff --git a/src/util/errors/HttpErrorUtil.ts b/src/util/errors/HttpErrorUtil.ts
new file mode 100644
index 000000000..a30bf64b1
--- /dev/null
+++ b/src/util/errors/HttpErrorUtil.ts
@@ -0,0 +1,38 @@
+import { BadRequestHttpError } from './BadRequestHttpError';
+import { createErrorMessage } from './ErrorUtil';
+import { HttpError } from './HttpError';
+import { InternalServerError } from './InternalServerError';
+
+/**
+ * Returns the HTTP status code corresponding to the error.
+ */
+export function getStatusCode(error: Error): number {
+  return HttpError.isInstance(error) ? error.statusCode : 500;
+}
+
+/**
+ * Combines a list of errors into a single HttpErrors.
+ * Status code depends on the input errors. If they all share the same status code that code will be re-used.
+ * If they are all within the 4xx range, 400 will be used, otherwise 500.
+ *
+ * @param errors - Errors to combine.
+ * @param messagePrefix - Prefix for the aggregate error message. Will be followed with an array of all the messages.
+ */
+export function createAggregateError(errors: Error[], messagePrefix = 'No handler supports the given input:'):
+HttpError {
+  const httpErrors = errors.map((error): HttpError =>
+    HttpError.isInstance(error) ? error : new InternalServerError(createErrorMessage(error)));
+  const joined = httpErrors.map((error: Error): string => error.message).join(', ');
+  const message = `${messagePrefix} [${joined}]`;
+
+  // Check if all errors have the same status code
+  if (httpErrors.length > 0 && httpErrors.every((error): boolean => error.statusCode === httpErrors[0].statusCode)) {
+    return new HttpError(httpErrors[0].statusCode, httpErrors[0].name, message);
+  }
+
+  // Find the error range (4xx or 5xx)
+  if (httpErrors.some((error): boolean => error.statusCode >= 500)) {
+    return new InternalServerError(message);
+  }
+  return new BadRequestHttpError(message);
+}
diff --git a/src/util/handlers/HandlerUtil.ts b/src/util/handlers/HandlerUtil.ts
index efb61ea52..dfc436cf8 100644
--- a/src/util/handlers/HandlerUtil.ts
+++ b/src/util/handlers/HandlerUtil.ts
@@ -1,36 +1,7 @@
-import { BadRequestHttpError } from '../errors/BadRequestHttpError';
 import { createErrorMessage, isError } from '../errors/ErrorUtil';
-import { HttpError } from '../errors/HttpError';
-import { InternalServerError } from '../errors/InternalServerError';
+import { createAggregateError } from '../errors/HttpErrorUtil';
 import type { AsyncHandler } from './AsyncHandler';
 
-/**
- * Combines a list of errors into a single HttpErrors.
- * Status code depends on the input errors. If they all share the same status code that code will be re-used.
- * If they are all within the 4xx range, 400 will be used, otherwise 500.
- *
- * @param errors - Errors to combine.
- * @param messagePrefix - Prefix for the aggregate error message. Will be followed with an array of all the messages.
- */
-export function createAggregateError(errors: Error[], messagePrefix = 'No handler supports the given input:'):
-HttpError {
-  const httpErrors = errors.map((error): HttpError =>
-    HttpError.isInstance(error) ? error : new InternalServerError(createErrorMessage(error)));
-  const joined = httpErrors.map((error: Error): string => error.message).join(', ');
-  const message = `${messagePrefix} [${joined}]`;
-
-  // Check if all errors have the same status code
-  if (httpErrors.length > 0 && httpErrors.every((error): boolean => error.statusCode === httpErrors[0].statusCode)) {
-    return new HttpError(httpErrors[0].statusCode, httpErrors[0].name, message);
-  }
-
-  // Find the error range (4xx or 5xx)
-  if (httpErrors.some((error): boolean => error.statusCode >= 500)) {
-    return new InternalServerError(message);
-  }
-  return new BadRequestHttpError(message);
-}
-
 /**
  * Finds a handler that can handle the given input data.
  * Otherwise an error gets thrown.
diff --git a/src/util/handlers/ParallelHandler.ts b/src/util/handlers/ParallelHandler.ts
index 3d78fb88b..b517257bb 100644
--- a/src/util/handlers/ParallelHandler.ts
+++ b/src/util/handlers/ParallelHandler.ts
@@ -12,12 +12,10 @@ export class ParallelHandler<TIn = void, TOut = void> extends AsyncHandler<TIn,
   }
 
   public async canHandle(input: TIn): Promise<void> {
-    // eslint-disable-next-line @typescript-eslint/promise-function-async
     await Promise.all(this.handlers.map((handler): Promise<void> => handler.canHandle(input)));
   }
 
   public async handle(input: TIn): Promise<TOut[]> {
-    // eslint-disable-next-line @typescript-eslint/promise-function-async
     return Promise.all(this.handlers.map((handler): Promise<TOut> => handler.handle(input)));
   }
 }
diff --git a/src/util/handlers/UnionHandler.ts b/src/util/handlers/UnionHandler.ts
index c165686fb..2a63656ca 100644
--- a/src/util/handlers/UnionHandler.ts
+++ b/src/util/handlers/UnionHandler.ts
@@ -1,31 +1,41 @@
+import { allFulfilled } from '../PromiseUtil';
 import { AsyncHandler } from './AsyncHandler';
-import { createAggregateError, filterHandlers, findHandler } from './HandlerUtil';
+import { filterHandlers, findHandler } from './HandlerUtil';
 
 // Helper types to make sure the UnionHandler has the same in/out types as the AsyncHandler type it wraps
-type ThenArg<T> = T extends PromiseLike<infer U> ? U : T;
+type Awaited<T> = T extends PromiseLike<infer U> ? U : T;
 type InType<T extends AsyncHandler<any, any>> = Parameters<T['handle']>[0];
-type OutType<T extends AsyncHandler<any, any>> = ThenArg<ReturnType<T['handle']>>;
-type HandlerType<T extends AsyncHandler> = AsyncHandler<InType<T>, OutType<T>>;
+type OutType<T extends AsyncHandler<any, any>> = Awaited<ReturnType<T['handle']>>;
 
 /**
  * Utility handler that allows combining the results of multiple handlers into one.
- * Will run all the handlers and then call the abstract `combine` function with the results,
- * which should return the output of the class.
- *
- * If `requireAll` is true, the handler will fail if any of the handlers do not support the input.
- * If `requireAll` is false, only the handlers that support the input will be called,
- * only if all handlers reject the input will this handler reject as well.
- * With `requireAll` set to false, the length of the input array
- * for the `combine` function is variable (but always at least 1).
+ * Will run the handlers and then call the abstract `combine` function with the results,
+ * which then generates the handler's output.
  */
 export abstract class UnionHandler<T extends AsyncHandler<any, any>> extends AsyncHandler<InType<T>, OutType<T>> {
   protected readonly handlers: T[];
   private readonly requireAll: boolean;
+  private readonly ignoreErrors: boolean;
 
-  protected constructor(handlers: T[], requireAll = false) {
+  /**
+   * Creates a new `UnionHandler`.
+   *
+   * When `requireAll` is false or `ignoreErrors` is true,
+   * the length of the input to `combine` can vary;
+   * otherwise, it is exactly the number of handlers.
+   *
+   * @param handlers - The handlers whose output is to be combined.
+   * @param requireAll - If true, will fail if any of the handlers do not support the input.
+                         If false, only the handlers that support the input will be called;
+   *                     will fail only if none of the handlers can handle the input.
+   * @param ignoreErrors - If true, ignores handlers that fail by omitting their output;
+   *                       if false, fails when any handlers fail.
+   */
+  public constructor(handlers: T[], requireAll = false, ignoreErrors = !requireAll) {
     super();
     this.handlers = handlers;
     this.requireAll = requireAll;
+    this.ignoreErrors = ignoreErrors;
   }
 
   public async canHandle(input: InType<T>): Promise<void> {
@@ -38,57 +48,21 @@ export abstract class UnionHandler<T extends AsyncHandler<any, any>> extends Asy
   }
 
   public async handle(input: InType<T>): Promise<OutType<T>> {
-    let handlers: HandlerType<T>[];
-    if (this.requireAll) {
-      // Handlers were already checked in canHandle
-      // eslint-disable-next-line prefer-destructuring
-      handlers = this.handlers;
-    } else {
-      handlers = await filterHandlers(this.handlers, input);
-    }
-
-    const results = await Promise.all(
-      handlers.map(async(handler): Promise<OutType<T>> => handler.handle(input)),
-    );
-
-    return this.combine(results);
-  }
-
-  public async handleSafe(input: InType<T>): Promise<OutType<T>> {
-    let handlers: HandlerType<T>[];
-    if (this.requireAll) {
-      await this.allCanHandle(input);
-      // eslint-disable-next-line prefer-destructuring
-      handlers = this.handlers;
-    } else {
-      // This will error if no handler supports the input
-      handlers = await filterHandlers(this.handlers, input);
-    }
-
-    const results = await Promise.all(
-      handlers.map(async(handler): Promise<OutType<T>> => handler.handle(input)),
-    );
-
-    return this.combine(results);
+    const handlers = this.requireAll ? this.handlers : await filterHandlers(this.handlers, input);
+    const results = handlers.map((handler): Promise<OutType<T>> => handler.handle(input));
+    return this.combine(await allFulfilled(results, this.ignoreErrors));
   }
 
   /**
    * Checks if all handlers can handle the input.
    * If not, throw an error based on the errors of the failed handlers.
    */
-  private async allCanHandle(input: InType<T>): Promise<void> {
-    const results = await Promise.allSettled(this.handlers.map(async(handler): Promise<HandlerType<T>> => {
-      await handler.canHandle(input);
-      return handler;
-    }));
-    if (results.some(({ status }): boolean => status === 'rejected')) {
-      const errors = results.map((result): Error => (result as PromiseRejectedResult).reason);
-      throw createAggregateError(errors);
-    }
+  protected async allCanHandle(input: InType<T>): Promise<void> {
+    await allFulfilled(this.handlers.map((handler): Promise<void> => handler.canHandle(input)));
   }
 
   /**
-   * Combine the results of the handlers into a single output.
+   * Combines the results of the handlers into a single output.
    */
   protected abstract combine(results: OutType<T>[]): Promise<OutType<T>>;
 }
diff --git a/test/integration/Setup.test.ts b/test/integration/Setup.test.ts
index 8cec739c4..b4be03ef3 100644
--- a/test/integration/Setup.test.ts
+++ b/test/integration/Setup.test.ts
@@ -51,7 +51,7 @@ describe('A Solid server with setup', (): void => {
 
     // Root access disabled
     res = await fetch(baseUrl);
-    expect(res.status).toBe(403);
+    expect(res.status).toBe(401);
 
     // Registration still possible
     const registerParams = { email, podName, password, confirmPassword: password, createWebId: true };
diff --git a/test/integration/WebSocketsProtocol.test.ts b/test/integration/WebSocketsProtocol.test.ts
index 7fa961cf3..2c678af4b 100644
--- a/test/integration/WebSocketsProtocol.test.ts
+++ b/test/integration/WebSocketsProtocol.test.ts
@@ -1,5 +1,5 @@
 import fetch from 'cross-fetch';
-import WebSocket from 'ws';
+import { WebSocket } from 'ws';
 import type { App } from '../../src/init/App';
 import { getPort } from '../util/Util';
 import { getDefaultVariables, getTestConfigPath, instantiateFromConfig } from './Config';
diff --git a/test/unit/authentication/UnionCredentialsExtractor.test.ts b/test/unit/authentication/UnionCredentialsExtractor.test.ts
index 1b69cb886..427f6ba40 100644
--- a/test/unit/authentication/UnionCredentialsExtractor.test.ts
+++ b/test/unit/authentication/UnionCredentialsExtractor.test.ts
@@ -43,4 +43,11 @@ describe('A UnionCredentialsExtractor', (): void => {
       [CredentialGroup.public]: {},
     });
   });
+
+  it('skips erroring handlers.', async(): Promise<void> => {
+    extractors[0].handle.mockRejectedValueOnce(new Error('error'));
+    await expect(extractor.handle(request)).resolves.toEqual({
+      [CredentialGroup.public]: {},
+    });
+  });
 });
diff --git a/test/unit/server/WebSocketServerFactory.test.ts b/test/unit/server/WebSocketServerFactory.test.ts
index 4e422aa0a..7605cf4cd 100644
--- a/test/unit/server/WebSocketServerFactory.test.ts
+++ b/test/unit/server/WebSocketServerFactory.test.ts
@@ -1,6 +1,6 @@
 import type { Server } from 'http';
 import request from 'supertest';
-import WebSocket from 'ws';
+import { WebSocket } from 'ws';
 import { BaseHttpServerFactory } from '../../../src/server/BaseHttpServerFactory';
 import type { HttpHandlerInput } from '../../../src/server/HttpHandler';
 import { HttpHandler } from '../../../src/server/HttpHandler';
diff --git a/test/unit/storage/patch/SparqlUpdatePatcher.test.ts b/test/unit/storage/patch/SparqlUpdatePatcher.test.ts
index 01386217a..6bb035a1f 100644
--- a/test/unit/storage/patch/SparqlUpdatePatcher.test.ts
+++ b/test/unit/storage/patch/SparqlUpdatePatcher.test.ts
@@ -2,6 +2,7 @@ import 'jest-rdf';
 import { namedNode, quad } from '@rdfjs/data-model';
 import arrayifyStream from 'arrayify-stream';
 import type { Quad } from 'rdf-js';
+import type { Algebra } from 'sparqlalgebrajs';
 import { translate } from 'sparqlalgebrajs';
 import { BasicRepresentation } from '../../../../src/http/representation/BasicRepresentation';
 import type { Representation } from '../../../../src/http/representation/Representation';
@@ -15,7 +16,7 @@ import { guardedStreamFrom } from '../../../../src/util/StreamUtil';
 function getPatch(query: string): SparqlUpdatePatch {
   const prefixedQuery = `prefix : <http://test.com/>\n${query}`;
   return {
-    algebra: translate(prefixedQuery, { quads: true }),
+    algebra: translate(prefixedQuery, { quads: true }) as Algebra.Update,
     data: guardedStreamFrom(prefixedQuery),
     metadata: new RepresentationMetadata(),
     binary: true,
diff --git a/test/unit/util/errors/ErrorUtil.test.ts b/test/unit/util/errors/ErrorUtil.test.ts
index be242152a..49eaf7c36 100644
--- a/test/unit/util/errors/ErrorUtil.test.ts
+++ b/test/unit/util/errors/ErrorUtil.test.ts
@@ -1,5 +1,4 @@
-import { assertError, createErrorMessage, getStatusCode, isError } from '../../../../src/util/errors/ErrorUtil';
-import { NotFoundHttpError } from '../../../../src/util/errors/NotFoundHttpError';
+import { assertError, createErrorMessage, isError } from '../../../../src/util/errors/ErrorUtil';
 
 describe('ErrorUtil', (): void => {
   describe('#isError', (): void => {
@@ -39,14 +38,4 @@ describe('ErrorUtil', (): void => {
       expect(createErrorMessage('apple')).toBe('Unknown error: apple');
     });
   });
-
-  describe('#getStatusCode', (): void => {
-    it('returns the corresponding status code for HttpErrors.', async(): Promise<void> => {
-      expect(getStatusCode(new NotFoundHttpError())).toBe(404);
-    });
-
-    it('returns 500 for other errors.', async(): Promise<void> => {
-      expect(getStatusCode(new Error('404'))).toBe(500);
-    });
-  });
 });
diff --git a/test/unit/util/errors/HttpErrorUtil.test.ts b/test/unit/util/errors/HttpErrorUtil.test.ts
new file mode 100644
index 000000000..d257bf9fb
--- /dev/null
+++ b/test/unit/util/errors/HttpErrorUtil.test.ts
@@ -0,0 +1,50 @@
+import { HttpError } from '../../../../src/util/errors/HttpError';
+import { createAggregateError, getStatusCode } from '../../../../src/util/errors/HttpErrorUtil';
+import { NotFoundHttpError } from '../../../../src/util/errors/NotFoundHttpError';
+
+describe('ErrorUtil', (): void => {
+  describe('createAggregateError', (): void => {
+    const error401 = new HttpError(401, 'UnauthorizedHttpError');
+    const error415 = new HttpError(415, 'UnsupportedMediaTypeHttpError');
+    const error501 = new HttpError(501, 'NotImplementedHttpError');
+    const error = new Error('noStatusCode');
+
+    it('throws an error with matching status code if all errors have the same.', async(): Promise<void> => {
+      expect(createAggregateError([ error401, error401 ])).toMatchObject({
+        statusCode: 401,
+        name: 'UnauthorizedHttpError',
+      });
+    });
+
+    it('throws an InternalServerError if one of the errors has status code 5xx.', async(): Promise<void> => {
+      expect(createAggregateError([ error401, error501 ])).toMatchObject({
+        statusCode: 500,
+        name: 'InternalServerError',
+      });
+    });
+
+    it('throws an BadRequestHttpError if all handlers have 4xx status codes.', async(): Promise<void> => {
+      expect(createAggregateError([ error401, error415 ])).toMatchObject({
+        statusCode: 400,
+        name: 'BadRequestHttpError',
+      });
+    });
+
+    it('interprets non-HTTP errors as internal errors.', async(): Promise<void> => {
+      expect(createAggregateError([ error ])).toMatchObject({
+        statusCode: 500,
+        name: 'InternalServerError',
+      });
+    });
+  });
+
+  describe('#getStatusCode', (): void => {
+    it('returns the corresponding status code for HttpErrors.', async(): Promise<void> => {
+      expect(getStatusCode(new NotFoundHttpError())).toBe(404);
+    });
+
+    it('returns 500 for other errors.', async(): Promise<void> => {
+      expect(getStatusCode(new Error('404'))).toBe(500);
+    });
+  });
+});
diff --git a/test/unit/util/handlers/HandlerUtil.test.ts b/test/unit/util/handlers/HandlerUtil.test.ts
index 9cef18305..718d03900 100644
--- a/test/unit/util/handlers/HandlerUtil.test.ts
+++ b/test/unit/util/handlers/HandlerUtil.test.ts
@@ -1,44 +1,8 @@
-import { HttpError } from '../../../../src/util/errors/HttpError';
 import type { AsyncHandler } from '../../../../src/util/handlers/AsyncHandler';
-import { createAggregateError, filterHandlers, findHandler } from '../../../../src/util/handlers/HandlerUtil';
+import { filterHandlers, findHandler } from '../../../../src/util/handlers/HandlerUtil';
 import { StaticAsyncHandler } from '../../../util/StaticAsyncHandler';
 
 describe('HandlerUtil', (): void => {
-  describe('createAggregateError', (): void => {
-    const error401 = new HttpError(401, 'UnauthorizedHttpError');
-    const error415 = new HttpError(415, 'UnsupportedMediaTypeHttpError');
-    const error501 = new HttpError(501, 'NotImplementedHttpError');
-    const error = new Error('noStatusCode');
-
-    it('throws an error with matching status code if all errors have the same.', async(): Promise<void> => {
-      expect(createAggregateError([ error401, error401 ])).toMatchObject({
-        statusCode: 401,
-        name: 'UnauthorizedHttpError',
-      });
-    });
-
-    it('throws an InternalServerError if one of the errors has status code 5xx.', async(): Promise<void> => {
-      expect(createAggregateError([ error401, error501 ])).toMatchObject({
-        statusCode: 500,
-        name: 'InternalServerError',
-      });
-    });
-
-    it('throws an BadRequestHttpError if all handlers have 4xx status codes.', async(): Promise<void> => {
-      expect(createAggregateError([ error401, error415 ])).toMatchObject({
-        statusCode: 400,
-        name: 'BadRequestHttpError',
-      });
-    });
-
-    it('interprets non-HTTP errors as internal errors.', async(): Promise<void> => {
-      expect(createAggregateError([ error ])).toMatchObject({
-        statusCode: 500,
-        name: 'InternalServerError',
-      });
-    });
-  });
-
   describe('findHandler', (): void => {
     let handlerTrue: AsyncHandler<any, any>;
     let handlerFalse: AsyncHandler<any, any>;
diff --git a/test/unit/util/handlers/UnionHandler.test.ts b/test/unit/util/handlers/UnionHandler.test.ts
index 27a803054..fc409e3d6 100644
--- a/test/unit/util/handlers/UnionHandler.test.ts
+++ b/test/unit/util/handlers/UnionHandler.test.ts
@@ -2,10 +2,6 @@ import type { AsyncHandler } from '../../../../src/util/handlers/AsyncHandler';
 import { UnionHandler } from '../../../../src/util/handlers/UnionHandler';
 
 class SimpleUnionHandler extends UnionHandler<AsyncHandler<any, string>> {
-  public constructor(handlers: AsyncHandler<any, any>[], requireAll?: boolean) {
-    super(handlers, requireAll);
-  }
-
   protected async combine(results: string[]): Promise<string> {
     return results.join('');
   }
@@ -61,4 +57,25 @@ describe('A UnionHandler', (): void => {
     handlers[0].canHandle.mockRejectedValue(new Error('bad request'));
     await expect(handler.handle(input)).resolves.toBe('ab');
   });
+
+  it('requires all handlers to succeed if requireAll is true.', async(): Promise<void> => {
+    handler = new SimpleUnionHandler(handlers, true);
+
+    handlers[0].handle.mockRejectedValue(new Error('bad request'));
+    await expect(handler.handleSafe(input)).rejects.toThrow('bad request');
+  });
+
+  it('does not require all handlers to succeed if ignoreErrors is true.', async(): Promise<void> => {
+    handler = new SimpleUnionHandler(handlers, true, true);
+
+    handlers[0].handle.mockRejectedValueOnce(new Error('bad request'));
+    await expect(handler.handleSafe(input)).resolves.toBe('b');
+
+    handlers[1].handle.mockRejectedValueOnce(new Error('bad request'));
+    await expect(handler.handleSafe(input)).resolves.toBe('a');
+
+    handlers[0].handle.mockRejectedValueOnce(new Error('bad request'));
+    handlers[1].handle.mockRejectedValueOnce(new Error('bad request'));
+    await expect(handler.handleSafe(input)).resolves.toBe('');
+  });
 });