diff --git a/.github/workflows/bench-pr.yml b/.github/workflows/bench-pr.yml
index 93cb4fec..7d9630b1 100644
--- a/.github/workflows/bench-pr.yml
+++ b/.github/workflows/bench-pr.yml
@@ -128,7 +128,7 @@ jobs:
           distribution: temurin
           java-version: 25 # kyoIntegration (KyoDiBench dep) targets JDK 25 since v0.15.0
       - name: Cache coursier + ivy + sbt boot
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
diff --git a/.github/workflows/bench-sweep.yml b/.github/workflows/bench-sweep.yml
index c2d025d1..58312ef8 100644
--- a/.github/workflows/bench-sweep.yml
+++ b/.github/workflows/bench-sweep.yml
@@ -124,7 +124,7 @@ jobs:
           distribution: temurin
           java-version: 25 # kyoIntegration (KyoDiBench dep) targets JDK 25 since v0.15.0
       - name: Cache coursier + ivy + sbt boot
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
index 419a8120..2ff77d9d 100644
--- a/.github/workflows/benchmarks.yml
+++ b/.github/workflows/benchmarks.yml
@@ -62,7 +62,7 @@ jobs:
           distribution: temurin
           java-version: 21
       - name: Cache coursier + ivy + sbt boot
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6978522b..995abc07 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -52,7 +52,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-25
         if: matrix.java == 'temurin@25'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -76,7 +76,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-17
         if: matrix.java == 'temurin@17'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -100,7 +100,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-21
         if: matrix.java == 'temurin@21'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -177,7 +177,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-25
         if: matrix.java == 'temurin@25'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -201,7 +201,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-17
         if: matrix.java == 'temurin@17'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -225,7 +225,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-21
         if: matrix.java == 'temurin@21'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -299,7 +299,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-25
         if: matrix.java == 'temurin@25'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -323,7 +323,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-17
         if: matrix.java == 'temurin@17'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -347,7 +347,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-21
         if: matrix.java == 'temurin@21'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -418,7 +418,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-25
         if: matrix.java == 'temurin@25'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -442,7 +442,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-17
         if: matrix.java == 'temurin@17'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -466,7 +466,7 @@ jobs:
       - name: Cache coursier + ivy + sbt boot
         id: coursier-cache-temurin-21
         if: matrix.java == 'temurin@21'
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
diff --git a/.github/workflows/deploy-site.yml b/.github/workflows/deploy-site.yml
index d6852b8e..2d94a58b 100644
--- a/.github/workflows/deploy-site.yml
+++ b/.github/workflows/deploy-site.yml
@@ -70,7 +70,7 @@ jobs:
           distribution: temurin
           java-version: 25
       - name: Cache coursier + ivy + sbt boot
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
diff --git a/.github/workflows/quality.yml b/.github/workflows/quality.yml
index 780bafa5..7582cbdc 100644
--- a/.github/workflows/quality.yml
+++ b/.github/workflows/quality.yml
@@ -61,7 +61,7 @@ jobs:
           distribution: temurin
           java-version: 25
       - name: Cache coursier + ivy + sbt boot
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier
@@ -97,7 +97,7 @@ jobs:
           distribution: temurin
           java-version: 25
       - name: Cache coursier + ivy + sbt boot
-        uses: actions/cache@v4
+        uses: actions/cache@v6
         with:
           path: |
             ~/.cache/coursier