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TSB-2026-40 The Schema Registry _schemas topic may expire after 7 days, when a cluster is created with auto_create_topics_enabled=true.

  • Updated

Summary: 

Starting in Redpanda v25.3.1 the Schema Registry performs a pre-flight check before creating its internal _schemas topic on initial startup.  On clusters that have auto_create_topics_enabled set to true when this check happens the _schemas topic gets created with the cluster default retention of 7 days and a cleanup policy of delete. The process that would normally create the _shemas topic sees that it is already created and leaves those values as is.

Clusters whose _schemas topic was created on a version prior to v25.3.1, and clusters where auto_create_topics_enabled is false (the Redpanda default; the Helm chart and Operator do not enable it), are not affected.

Severity: 

High

Redpanda Products Affected:

  • Redpanda Self-Managed - Enterprise
  • Redpanda Self-Managed - Community

Redpanda Cloud clusters are managed by Redpanda; auto_create_topics_enabled is not supported on BYOC and Dedicated clusters, and have been manually reviewed. 

Release Affected:

Redpanda versions 25.3.1+,

Redpanda versions 26.1.1 - 26.1.13 (26.1.14 releasing 07-24-2026)

Identification:

Run the following against your cluster:

rpk cluster config get auto_create_topics_enabled
rpk topic describe _schemas -c

You are impacted if auto_create_topics_enabled=true and _schemas shows the following, where the DEFAULT_CONFIG source indicates the topic was auto-created with cluster defaults:

rpk cluster config get auto_create_topics_enabled

true

rpk topic describe _schemas -c
cleanup.policy   delete      DEFAULT_CONFIG
retention.ms     604800000   DEFAULT_CONFIG

A correctly configured _schemas topic shows cleanup.policy compact and retention.ms -1 with source DYNAMIC_TOPIC_CONFIG.

Impact: 

The _schemas topic stores all Schema Registry data (schemas, subjects, versions, and compatibility configuration). With cleanup.policy=delete and the default 7-day retention, schema records are permanently deleted when retention is applied. Registered schemas can silently disappear from the Schema Registry, after which producers and consumers relying on schema IDs may fail with schema-not-found errors.

Action required: 

If the Identification steps above show your _schemas topic has the incorrect configuration, correct it immediately, before retention removes schema data:

rpk topic alter-config _schemas \
—-set cleanup.policy=compact \
--set retention.ms=-1 \
—-set compression.type=none

Then re-run rpk topic describe _schemas -c to verify the change.

KEY                SOURCE                 VALUE
cleanup.policy     DYNAMIC_TOPIC_CONFIG   compact
retention.ms       DYNAMIC_TOPIC_CONFIG   -1
compression.type   DYNAMIC_TOPIC_CONFIG   none

Additionally, Redpanda defaults auto_create_topics_enabled to false to avoid spurious topic creation. If auto-creation is not needed by your applications or ecosystem, you can disable it with the command below:

rpk cluster config set auto_create_topics_enabled false

If auto-creation must remain enabled, verify (and if necessary correct) the _schemas topic configuration on any newly created cluster before registering schemas.

This will be fixed in Redpanda version 26.1.14, and all future versions and will be released on 07-24-2026.  If you are impacted, upgrading will not resolve the retention settings, you will need to run the commands above.

Questions? If you have any questions on this TSB, or need further guidance, please contact Redpanda Support