diff --git a/.github/workflows/sdk-wheels.yml b/.github/workflows/sdk-wheels.yml
index 3cff4cb..74b3a2a 100644
--- a/.github/workflows/sdk-wheels.yml
+++ b/.github/workflows/sdk-wheels.yml
@@ -69,14 +69,17 @@ jobs:
       # the macOS runners), the whole build fails before compiling anything. Native builds
       # therefore start sccache themselves and drop the compiler cache if it does not come
       # up; only the manylinux containers keep the action input. sccache's GHA backend
-      # reads the two ACTIONS_* values, which shell steps do not get without this export.
+      # reads these ACTIONS_* values, which shell steps do not get without this export.
+      # ACTIONS_CACHE_SERVICE_V2 selects the current cache API; without it the backend
+      # falls back to the retired v1 endpoint and every lookup misses.
       - name: Expose the Actions cache credentials to sccache
         if: runner.os != 'Linux'
         uses: actions/github-script@v7
         with:
           script: |
-            core.exportVariable('ACTIONS_RESULTS_URL', process.env.ACTIONS_RESULTS_URL || '');
-            core.exportVariable('ACTIONS_RUNTIME_TOKEN', process.env.ACTIONS_RUNTIME_TOKEN || '');
+            for (const name of ['ACTIONS_RESULTS_URL', 'ACTIONS_RUNTIME_TOKEN', 'ACTIONS_CACHE_URL', 'ACTIONS_CACHE_SERVICE_V2']) {
+              core.exportVariable(name, process.env[name] || '');
+            }
       - name: Start sccache (best effort)
         if: runner.os != 'Linux'
         shell: bash
@@ -210,14 +213,17 @@ jobs:
       # the macOS runners), the whole build fails before compiling anything. Native builds
       # therefore start sccache themselves and drop the compiler cache if it does not come
       # up; only the manylinux containers keep the action input. sccache's GHA backend
-      # reads the two ACTIONS_* values, which shell steps do not get without this export.
+      # reads these ACTIONS_* values, which shell steps do not get without this export.
+      # ACTIONS_CACHE_SERVICE_V2 selects the current cache API; without it the backend
+      # falls back to the retired v1 endpoint and every lookup misses.
       - name: Expose the Actions cache credentials to sccache
         if: runner.os != 'Linux'
         uses: actions/github-script@v7
         with:
           script: |
-            core.exportVariable('ACTIONS_RESULTS_URL', process.env.ACTIONS_RESULTS_URL || '');
-            core.exportVariable('ACTIONS_RUNTIME_TOKEN', process.env.ACTIONS_RUNTIME_TOKEN || '');
+            for (const name of ['ACTIONS_RESULTS_URL', 'ACTIONS_RUNTIME_TOKEN', 'ACTIONS_CACHE_URL', 'ACTIONS_CACHE_SERVICE_V2']) {
+              core.exportVariable(name, process.env[name] || '');
+            }
       - name: Start sccache (best effort)
         if: runner.os != 'Linux'
         shell: bash