Resolve Solr core creation failure caused by circuitBreaker misconfiguration in solrconfig.xml

Issue

Solr core creation fails when importing an application into Fusion 5.9.14. The error output includes the following message:

Error CREATEing SolrCore 'homepage_suggestions_shard1_replica_n1': Unable to create core [homepage_suggestions_shard1_replica_n1] Caused by: [solrconfig.xml] circuitBreaker: missing mandatory attribute 'class'

This prevents the successful deployment of apps or collections migrated from earlier Fusion versions.

Diagnosis

This error is caused by an invalid <circuitBreaker> block in the solrconfig.xml file. The tag may be present without the required class attribute or with only disabled content. Solr 9.6.1, introduced in Fusion 5.9.14, enforces stricter validation rules for this tag and fails to create the core if misconfigured.

To confirm the issue:

• Open the application archive (e.g., homepage_app.zip)

• Locate the configset directory for the collection (e.g., configsets/homepage_collection)

• Open solrconfig.xml and search for the <circuitBreaker> tag

• Check if it lacks a class attribute or contains disabled configurations

Environment

• Fusion 5.9.14 and above

• Solr 9.6.1

• Kubernetes 1.29

• Applies when migrating or importing apps from earlier versions such as Fusion 5.9.4

Cause

In Fusion versions prior to 5.9.5, the <circuitBreaker> tag may have been present in the solrconfig.xml file but unused or partially configured. As of Solr 9.6.1, this tag is considered invalid unless fully defined with a required class attribute. Solr fails to create the core if this validation fails.

Resolution

To resolve this issue, remove the entire <circuitBreaker> section from the solrconfig.xml file before importing the application into Fusion 5.9.14.

Remove the <circuitBreaker> block

• Unzip the app archive.

• Navigate to the configsets/<collection_name> directory.

• Open solrconfig.xml in a text editor.

• Search for the <circuitBreaker> block.

• Remove the entire tag and its contents. For example, delete:

<circuitBreaker>
  <!-- Any nested content or comments -->
</circuitBreaker>

• Save the file.

• Re-zip the application directory structure exactly as it was originally.

• Re-import the app into Fusion.

After completing these steps, the import process should succeed without triggering the Solr core creation error.

For additional reference, see the Fusion 5.9.5 release notes, which note changes in Solr configuration validation requirements.