diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 68f8bc99..13599bc8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -119,14 +119,38 @@ jobs:
             git config --global pack.threads 0
             ! command -v cmake &> /dev/null || echo "B2_FLAGS=--nowide-enable-cmake" >> $GITHUB_ENV
 
+            if [[ "${{matrix.container}}" == "ubuntu:16.04" ]] || [[ "${{matrix.container}}" == "ubuntu:18.04" ]]; then
+              # Ubuntu 16/18 can't run Node 20, so stick to older actions: https://github.com/actions/checkout/issues/1590
+              echo "GHA_USE_NODE_20=false" >> $GITHUB_ENV
+            else
+              echo "GHA_USE_NODE_20=true" >> $GITHUB_ENV
+            fi
+
       - uses: actions/checkout@v3
+        if: env.GHA_USE_NODE_20 == 'false'
+        with:
+          # For coverage builds fetch the whole history, else only 1 commit using a 'fake ternary'
+          fetch-depth: ${{ matrix.coverage && '0' || '1' }}
+
+      - uses: actions/checkout@v4
+        if: env.GHA_USE_NODE_20 == 'true'
         with:
           # For coverage builds fetch the whole history, else only 1 commit using a 'fake ternary'
           fetch-depth: ${{ matrix.coverage && '0' || '1' }}
 
       - name: Cache ccache
         uses: actions/cache@v3
-        if: env.B2_USE_CCACHE
+        if: env.B2_USE_CCACHE && env.GHA_USE_NODE_20 == 'false'
+        with:
+          path: ~/.ccache
+          key: ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}-${{github.sha}}
+          restore-keys: |
+            ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}-
+            ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}
+
+      - name: Cache ccache
+        uses: actions/cache@v4
+        if: env.B2_USE_CCACHE && env.GHA_USE_NODE_20 == 'true'
         with:
           path: ~/.ccache
           key: ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}-${{github.sha}}
@@ -136,6 +160,15 @@ jobs:
 
       - name: Fetch Boost.CI
         uses: actions/checkout@v3
+        if: env.GHA_USE_NODE_20 == 'false'
+        with:
+          repository: boostorg/boost-ci
+          ref: master
+          path: boost-ci-cloned
+
+      - name: Fetch Boost.CI
+        uses: actions/checkout@v4
+        if: env.GHA_USE_NODE_20 == 'true'
         with:
           repository: boostorg/boost-ci
           ref: master
@@ -260,7 +293,7 @@ jobs:
     runs-on: windows-latest
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup MSYS2 environment
         uses: msys2/setup-msys2@v2
@@ -271,7 +304,7 @@ jobs:
           pacboy: gcc:p cmake:p ninja:p
 
       - name: Fetch Boost.CI
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: boostorg/boost-ci
           ref: master
@@ -320,9 +353,9 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Fetch Boost.CI
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: boostorg/boost-ci
           ref: master
diff --git a/.github/workflows/ci_tests.yml b/.github/workflows/ci_tests.yml
index 39e0a4f5..50c4a39a 100644
--- a/.github/workflows/ci_tests.yml
+++ b/.github/workflows/ci_tests.yml
@@ -48,10 +48,10 @@ jobs:
       DEP_DIR: ${{github.workspace}}/dependencies
       BOOST_VERSION: 1.56.0
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - name: Sanity check version
       run: grep -E 'set\(_version [0-9]' CMakeLists.txt
-    - uses: actions/cache@v1
+    - uses: actions/cache@v4
       id: cache-boost
       with:
         path: ${{env.DEP_DIR}}
@@ -64,7 +64,7 @@ jobs:
       if: matrix.standalone == 'Boost'
       run: echo "BOOST_ROOT=${DEP_DIR//\\/\/}/boost_${BOOST_VERSION//./_}" >> $GITHUB_ENV
     # Install Boost
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
       if: matrix.standalone == 'Boost' && steps.cache-boost.outputs.cache-hit != 'true'
       with:
         repository: boostorg/boost
@@ -125,7 +125,7 @@ jobs:
   CreateDocuTest:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v4
       - name: Create documentation
         run: |
             sudo apt-get install -y doxygen
@@ -134,9 +134,9 @@ jobs:
   CreateBoostDocuTest:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Fetch Boost.CI
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         with:
           repository: boostorg/boost-ci
           ref: master
@@ -153,7 +153,7 @@ jobs:
   CheckFormatting:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: DoozyX/clang-format-lint-action@v0.11
         with:
           exclude: './doc'
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 30523234..1dd3bc94 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -18,7 +18,7 @@ jobs:
       DEP_DIR: ${{github.workspace}}/dependencies
       BOOST_VERSION: 1.56.0
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Extract tag name
         id: get_tag
         run: |