elasticsearch/docs/release-notes/known-issues.md

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navigation_title: "Known issues" mapped_pages:

• https://www.elastic.co/guide/en/elasticsearch/reference/current/es-release-notes.html ---

Elasticsearch known issues [elasticsearch-known-issues]

Known issues are significant defects or limitations that may impact your implementation. These issues are actively being worked on and will be addressed in a future release. Review the Elasticsearch known issues to help you make informed decisions, such as upgrading to a new version.

9.1.1 [elasticsearch-9.1.1-known-issues]

• An optimization introduced in 9.1.0 contains a bug that causes merges to fail for shrunk TSDB and LogsDB indices.
  

Possible temporary workarounds include:

• Configure the ILM policy to not perform force merges after shrinking TSDB or LogsDB indices.
• Add -Dorg.elasticsearch.index.codec.tsdb.es819.ES819TSDBDocValuesConsumer.enableOptimizedMerge=false as a Java system property to all data nodes in the cluster and perform a rolling restart.
  • Important: Remove this property when upgrading to the fixed version to re-enable merge optimization. Otherwise, merges will be slower.
    

The bug is addressed in version 9.1.2.

9.1.0 [elasticsearch-9.1.0-known-issues]

• An optimization introduced in 9.1.0 contains a bug that causes merges to fail for shrunk TSDB and LogsDB indices.
  

Possible temporary workarounds include:

• Configure the ILM policy to not perform force merges after shrinking TSDB or LogsDB indices.
• Add -Dorg.elasticsearch.index.codec.tsdb.es819.ES819TSDBDocValuesConsumer.enableOptimizedMerge=false as a Java system property to all data nodes in the cluster and perform a rolling restart.
  • Important: Remove this property when upgrading to the fixed version to re-enable merge optimization. Otherwise, merges will be slower.
    

The bug is addressed in version 9.1.2.

• The -Dvector.rescoring.directio JVM option is enabled (set to true) by default. When used with bbq_hnsw type vector indices, this can cause significant search performance degradation; particularly when enough memory is available to hold all vector data. In some cases, kNN search latency can increase by as much as 10x. To mitigate this, set the JVM option -Dvector.rescoring.directio=false on all search nodes and restart them. This option can be removed in 9.1.1.

How do I know if my index vector type is bbq_hnsw?

• Prior to 9.1, the vector type had to be explicitly set to bbq_hnsw. Starting with 9.1, bbq_hnsw is the default vector type for dense vectors with more than 384 dimensions in new indices, unless another type is specified.

9.0.3 [elasticsearch-9.0.3-known-issues]

• A bug in the merge scheduler in Elasticsearch 9.0.3 may prevent shards from closing when there isn’t enough disk space to complete a merge. As a result, operations such as closing or relocating an index may hang until sufficient disk space becomes available. To mitigate this issue, the disk space checker is disabled by default in 9.0.3 by setting indices.merge.disk.check_interval to 0 seconds. Manually enabling this setting is not recommended.

This issue is planned to be fixed in future patch release #129613

• A bug in the ES|QL STATS command may yield incorrect results. The bug only happens in very specific cases that follow this pattern: STATS ... BY keyword1, keyword2, i.e. the command must have exactly two grouping fields, both keywords, where the first field has high cardinality (more than 65k distinct values).

The bug is described in detail in this issue. The problem was introduced in 8.16.0 and fixed in 8.17.9, 8.18.7, 9.0.4.

Possible workarounds include:

• switching the order of the grouping keys (eg. STATS ... BY keyword2, keyword1, if the keyword2 has a lower cardinality)
• reducing the grouping key cardinality, by filtering out values before STATS

9.0.0 [elasticsearch-9.0.0-known-issues]

• Elasticsearch on Windows might fail to start, or might forbid some file-related operations, when referencing paths with a case different from the one stored by the filesystem. Windows treats paths as case-insensitive, but the filesystem stores them with case. Entitlements, the new security system used by Elasticsearch, treat all paths as case-sensitive, and can therefore prevent access to a path that should be accessible.

For example: If Elasticsearch is installed in C:\ELK\elasticsearch, and you try to launch it as c:\elk\elasticsearch\bin\elasticsearch.bat, you will get a NotEntitledException while booting. This is because Elasticsearch blocks access to c:\elk\elasticsearch, because does not match C:\ELK\elasticsearch. \ This issue will be fixed in a future patch release (see PR #126990).

As a workaround, make sure that all paths you specify have the same casing as the paths stored in the filesystem. Files and directory names should be entered as they appear in Windows Explorer or in a command prompt. This applies to paths specified in the command line, config files, environment variables and secure settings.

• Active Directory authentication is blocked by default. Entitlements, the new security system used by Elasticsearch, has a policy for the x-pack-core module that is too restrictive, and does not allow the LDAP library used for AD authentication to perform outbound network connections. This issue will be fixed in a future patch release (see PR #126992).

As a workaround, you can temporarily patch the policy using a JVM option:

1. Create a file called ${ES_CONF_PATH}/jvm_options/workaround-127061.options.

2. Add the following line to the new file:

    -Des.entitlements.policy.x-pack-core=dmVyc2lvbnM6CiAgLSA4LjE4LjAKICAtIDkuMC4wCnBvbGljeToKICB1bmJvdW5kaWQubGRhcHNkazoKICAgIC0gc2V0X2h0dHBzX2Nvbm5lY3Rpb25fcHJvcGVydGllcwogICAgLSBvdXRib3VuZF9uZXR3b3Jr
   

For information about editing your JVM settings, refer to JVM settings.

• Users upgrading from an Elasticsearch cluster that had previously been on a version between 7.10.0 and 7.12.1 may see that Watcher will not start on 9.x. The solution is to run the following commands in Kibana Dev Tools (or the equivalent using curl):

   DELETE _index_template/.triggered_watches
   DELETE _index_template/.watches
   POST /_watcher/_start
  

• A bug in the ES|QL STATS command may yield incorrect results. The bug only happens in very specific cases that follow this pattern: STATS ... BY keyword1, keyword2, i.e. the command must have exactly two grouping fields, both keywords, where the first field has high cardinality (more than 65k distinct values).

The bug is described in detail in this issue. The problem was introduced in 8.16.0 and fixed in 8.17.9, 8.18.7, 9.0.4.

Possible workarounds include:

* switching the order of the grouping keys (eg. `STATS ... BY keyword2, keyword1`, if the `keyword2` has a lower cardinality)
* reducing the grouping key cardinality, by filtering out values before STATS