diff --git a/.github/workflows/publish_schema.yml b/.github/workflows/publish_schema.yml
index ab0cd3b461..cb5aca1db6 100644
--- a/.github/workflows/publish_schema.yml
+++ b/.github/workflows/publish_schema.yml
@@ -28,7 +28,7 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
           filter: "blob:none"
diff --git a/.github/workflows/schemacode_ci.yml b/.github/workflows/schemacode_ci.yml
index 5c36f45abb..1d4995043f 100644
--- a/.github/workflows/schemacode_ci.yml
+++ b/.github/workflows/schemacode_ci.yml
@@ -29,7 +29,7 @@ jobs:
       attestations: write
       id-token: write
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           fetch-depth: 0
       - name: Install the latest version of uv
@@ -62,7 +62,7 @@ jobs:
             python-version: 3.13
     name: ${{ matrix.os }} with Python ${{ matrix.python-version }}
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set up Python ${{ matrix.python-version }} (uv)
         uses: astral-sh/setup-uv@v6
@@ -74,7 +74,7 @@ jobs:
         run: python -c "import sys; print(sys.version)"
 
       - name: "Fetch packages"
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: Packages
           path: dist
@@ -95,7 +95,7 @@ jobs:
         working-directory: tools/schemacode
 
       - name: Upload artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: unit_${{ matrix.os }}_${{ matrix.python-version }}
           path: tools/schemacode/coverage.xml
@@ -112,7 +112,7 @@ jobs:
 
     steps:
       - name: Download packages built by build-and-inspect-python-package
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: Packages
           path: dist
@@ -131,7 +131,7 @@ jobs:
     runs-on: ubuntu-latest
     name: Validate schema
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Set Up Python environment
         uses: actions/setup-python@v6
@@ -150,7 +150,7 @@ jobs:
         working-directory: tools/schemacode
 
       - name: Upload artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v5
         with:
           name: schema_validation
           path: tools/schemacode/coverage.xml
@@ -162,10 +162,10 @@ jobs:
     needs: [test, validate_schema]
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Download artifacts
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
 
       - name: Upload to CodeCov
         uses: codecov/codecov-action@v5
diff --git a/.github/workflows/shellcheck.yml b/.github/workflows/shellcheck.yml
index 9a4656a485..79dd6522d8 100644
--- a/.github/workflows/shellcheck.yml
+++ b/.github/workflows/shellcheck.yml
@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Install dependencies
         run: |
           sudo apt update && sudo apt install -y shellcheck
diff --git a/.github/workflows/validation.yml b/.github/workflows/validation.yml
index 4dfc8efeac..1c354c471b 100644
--- a/.github/workflows/validation.yml
+++ b/.github/workflows/validation.yml
@@ -16,15 +16,15 @@ jobs:
   codespell:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: codespell-project/actions-codespell@master
 
   # Markdown formatting
   remark:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
         with:
           node-version: 22
       - name: Install dependencies
@@ -36,7 +36,7 @@ jobs:
   yamllint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: astral-sh/setup-uv@v6
       - name: Lint yml files in src/schema
         run: uvx yamllint -f standard src/schema/ -c .yamllint.yml
@@ -45,7 +45,7 @@ jobs:
   python-style:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: astral-sh/setup-uv@v6
       - run: uvx ruff format --diff
       - run: uvx ruff check
@@ -54,7 +54,7 @@ jobs:
   latin-phrases:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: astral-sh/setup-uv@v6
       - name: Check for Latin phrases
         run: uv run tools/no-bad-latin.py
@@ -63,7 +63,7 @@ jobs:
   validate_cff:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: astral-sh/setup-uv@v6
       - name: Validate CITATION.cff
         run: uvx cffconvert --validate