EC
MISCONF
RedisCRITICALPersistenceHIGH confidence

Redis is configured to save RDB snapshots but is unable to persist on disk

Production Risk

High. This error halts all write operations, effectively making the database read-only and potentially causing cascading failures in applications.

What this means

This critical error indicates that Redis is configured to take RDB snapshots but the last attempt to save to disk failed. To prevent data loss divergence, Redis blocks all write commands until the issue is resolved.

Why it happens
  1. 1Insufficient disk space on the volume where the RDB file is saved.
  2. 2Incorrect file permissions; the Redis process does not have write access to its working directory or the RDB file.
  3. 3A hardware fault with the underlying storage.
  4. 4The Redis process was terminated (e.g., by OOM killer) during a save operation.
How to reproduce

A client attempts to execute a SET command after a background save (BGSAVE) has failed due to disk space issues.

trigger — this will error
trigger — this will error
# BGSAVE fails in the background...
# Later, a client sends:
SET user:1 "john"

expected output

(error) MISCONF Redis is configured to save RDB snapshots, but is currently unable to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.

Fix 1

Resolve the underlying disk issue

WHEN This is the primary and most important fix

Resolve the underlying disk issue
# Check disk space
df -h

# Check directory permissions
ls -ld /var/lib/redis

Why this works

Freeing up disk space or fixing permissions will allow the next snapshot attempt to succeed. Once a BGSAVE completes successfully, Redis will automatically re-enable writes.

Fix 2

Dynamically disable the stop-writes-on-bgsave-error feature

WHEN As a temporary measure to restore service while fixing the root cause

Dynamically disable the stop-writes-on-bgsave-error feature
CONFIG SET stop-writes-on-bgsave-error no

Why this works

This command tells Redis to allow writes even if RDB snapshotting is failing. This is dangerous as it means a crash could lead to significant data loss, but it can restore service availability in an emergency.

What not to do

✕ Ignore the error and only use the temporary fix

Disabling 'stop-writes-on-bgsave-error' exposes you to major data loss. It's a temporary patch, not a solution. The root cause of the save failure must be fixed.

Sources
Official documentation ↗

redis.conf 'stop-writes-on-bgsave-error' directive

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