Redis "MISCONF Redis is configured to save RDB snapshots" in CI

A background save (BGSAVE) failed, and because stop-writes-on-bgsave-error is on by default, Redis stops accepting writes and returns "MISCONF Redis is configured to save RDB snapshots, but it is currently unable to persist on disk." In CI this is usually a read-only or full container filesystem.

What this error means

Writes suddenly fail with "MISCONF Redis is configured to save RDB snapshots, but it is currently unable to persist on disk. Commands that may modify the data set are disabled." while reads keep working.

redis-cli

(error) MISCONF Redis is configured to save RDB snapshots, but it is currently
not able to persist on disk. Commands that may modify the data set are disabled,
because this instance is configured to report errors during writes if the RDB
snapshotting fails (stop-writes-on-bgsave-error option).

Common causes

The container filesystem is read-only or full

A read-only rootfs or a full disk means Redis cannot write dump.rdb, so BGSAVE fails and writes are frozen.

Persistence is enabled but not needed for tests

RDB snapshots are on by default; for ephemeral CI data they only create a way to fail when the disk misbehaves.

How to fix it

Disable persistence for CI

Turn off RDB saving so Redis never needs to write to disk during tests.

.github/workflows/ci.yml

services:
  redis:
    image: redis:7
    options: --save "" --appendonly no
    ports: ['6379:6379']

Do not stop writes when a save fails

If you must keep snapshots, allow writes to continue even when BGSAVE fails.

Terminal

redis-cli config set stop-writes-on-bgsave-error no

How to prevent it

Run CI Redis with persistence off (--save "") for ephemeral test data.
Ensure the container dir is writable if snapshots are actually needed.
Watch disk usage on the runner so BGSAVE does not hit a full filesystem.