Yesterday our workflows started failing when some steps were unable to restore from cache. Rerunning the workflow with debugging enabled revealed that action/cache@v4 was using different versions of its backing service— sometimes v1, other times v2. It seems the failure occurs when one version of the backing service is used to save the cache, and another version is used to restore from cache.

All the steps in the workflow are using the same version of the action (v4).

Incidentally, downgrading to action/cache@v4.1.2 seemed to solve the problem, but that version is deprecated and so was affected by the brownout today.

Here the cache is initialized with v1

… later in the same run