Periodic "FATAL" level messages in Keycloak logs #45758

darius-m · 2026-01-26T15:14:21Z

darius-m
Jan 26, 2026

I've tried upgrading Keycloak to 25.6.1 and 25.6.2 and testing some of the newer logging options. Among other things, I've noticed that the following messages are logged every ~45 seconds. Is this expected behavior or can this be a result of a misconfiguration somewhere? From what I could find, the messages seem to be created by one of the features introduced in 25.6.1 (https://github.com/keycloak/keycloak/blame/26.5.2/model/infinispan/src/main/java/org/keycloak/models/sessions/infinispan/expiration/ConsistentHash.java#L151) and appears to be normal functionality, but I can't really tell since I didn't dive too deep into the code.

2026-01-23 08:33:33,994 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573
2026-01-23 08:34:17,728 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:6bec07cc-0ed8-438d-974f-5a62fc7ee6ec
2026-01-23 08:34:18,990 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (timeout-thread--p4-t1) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573
2026-01-23 08:34:18,994 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573
2026-01-23 08:35:02,727 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:6bec07cc-0ed8-438d-974f-5a62fc7ee6ec
2026-01-23 08:35:03,990 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (timeout-thread--p4-t1) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573
2026-01-23 08:35:03,994 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573
2026-01-23 08:35:47,728 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:6bec07cc-0ed8-438d-974f-5a62fc7ee6ec
2026-01-23 08:35:48,990 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (timeout-thread--p4-t1) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573
2026-01-23 08:35:48,995 FATAL [org.keycloak.models.sessions.infinispan.expiration.ConsistentHash] (HotRod-client-async-pool-1-3) Adding a keycloak instance with ID: node:f6e908e7-65da-4a16-a928-166aef1e5573

Is the log level correct if this is normal functionality? It generates quite a few lines of logs and it must be explicitly disabled since it's set to FATAL. The logs are configured using the following settings:

# Log configuration
log=console,file
log-level=INFO,org.keycloak.events:DEBUG

log-console-level=INFO
log-console-output=default

log-file=/var/log/keycloak/keycloak-ecs.log
log-file-level=DEBUG
log-file-output=json
log-file-json-format=ecs

log-mdc-enabled=true
log-mdc-keys=realmName,clientId,userId,ipAddress,org

log-console-include-mdc=true
log-file-include-mdc=true
log-syslog-include-mdc=true

# Log audit events using JBoss logging to the log file
spi-events-listener-jboss-logging-success-level=debug
spi-events-listener-jboss-logging-error-level=warn

Also, is there any way to link the UUID (appears to be UUIDv4, so it's random) to a specific Keycloak node? The logs sometimes also show a different UUID - the systems are configured in a multi-cluster deployment with external Infinispan (two nodes, hosting both Infinispan and Keycloak on each instance).

Answered by pruivo

Jan 27, 2026

@darius-m @opravil-jan my bad, I changed to fatal for manual testing and forgot to change back to debug.

View full answer

opravil-jan · 2026-01-27T10:53:35Z

opravil-jan
Jan 27, 2026

Hi,
We are seeing the same error messages and serious performance degradation when upgrading from keycloak 26.4.x to 26.5.2. Can anyone take a look at it, please?

Thank you

6 replies

darius-m Jan 27, 2026
Author

@ahus1 @pruivo could you confirm whether this is expected behavior? I haven't seen any reported issue around it, so I'm not sure how to confirm whether there's an issue with my configs.

pruivo Jan 27, 2026
Collaborator

@darius-m @opravil-jan my bad, I changed to fatal for manual testing and forgot to change back to debug.

Answer selected by ahus1

ahus1 Jan 27, 2026
Collaborator

@darius-m - sorry for missing that in a review. For those items, it is usually better to open a bug directly. We have automated processes and SLAs to review those, while there is nothing like that for discussions.

I see that Pedro opened an issue here: #45780

pruivo Jan 27, 2026
Collaborator

I'm sorry for the trouble. I've opened pull requests with the fix.

darius-m Jan 27, 2026
Author

Sorry for opening a discussion instead of an issue, but I wasn't sure whether the issue was caused by a weird configuration on my end.
Thank you for the prompt answers.

ahus1 Jan 29, 2026
Collaborator

No worries. The intent of my comment was that you'll get more predictable response times when creating an error. A discussion might go unnoticed for some time.

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Periodic "FATAL" level messages in Keycloak logs #45758

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Periodic "FATAL" level messages in Keycloak logs #45758

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