Cannot create a collection in Fusion 5.9.x versions due to missing _fusion_default config set

Issue

After upgrading to Fusion 5.9.x, attempts to create a new collection using the default settings via Collections Manager may result in the following error:

API ERROR  
Code: ERR-0001  
Status: 500 Internal Server Error  
Error: Error from server at http://<solr-host>:8983/solr: Base ConfigSet does not exist: _fusion_default

This prevents creation of new collections using the “Base ConfigSet” option in the Fusion UI.

Diagnosis

To confirm whether the issue is caused by a missing _fusion_default config set:

1. Open a shell session to a Solr pod in your Fusion deployment:

   kubectl exec -it <namespace>-solr-0 -n <namespace> -- /bin/sh

2. Run the following command to list all config sets in ZooKeeper:

   curl http://<namespace>-solr-headless:8983/solr/admin/configs?action=LIST&wt=json

3. Check if _fusion_default appears in the list of configSets. If it is missing, this confirms the root cause.

Environment

• Fusion 5.9.x

• Kubernetes-based deployment (e.g., AKS, EKS, GKE)

• Applies to self-hosted Fusion environments

• Observed after in-place upgrades from Fusion 5.9.x

Cause

During some in-place upgrades to Fusion 5.9.x, the _fusion_default config set may not be propagated to ZooKeeper. This config set is required for default collection creation via the Fusion UI.

Attempts to recreate it manually using Solr APIs can fail due to inherited authentication requirements from the *_default base config set.

Resolution

Use the provided Fusion script sync-configsets-with-zk.sh to re-upload the _fusion_default config set from the pod to ZooKeeper.

1. Check if the sync script exists

Run this command in one of your Solr pods:

kubectl exec <solr_pod> -- cat /opt/lucidworks/sync-configsets-with-zk.sh

You should see a small Bash script ending with:

exec java ${SOLR_OPTS:-} ${SOLR_ZK_CREDS_AND_ACLS:-} ${SOLR_TOOL_OPTS:-} -cp "${CLASSPATH}" "${LOG_OPT}" "${MAIN_CLASS}"

2. Execute the sync script

If the script exists, run the following command to initiate config set synchronization:

kubectl exec <solr_pod> -- /opt/lucidworks/sync-configsets-with-zk.sh

This script scans for any local _fusion_* config sets (including _fusion_default) and uploads them to ZooKeeper, overwriting them only if necessary.

3. Verify the result

Once complete, verify the config set is now available in ZooKeeper:

curl http://<namespace>-solr-headless:8983/solr/admin/configs?action=LIST&wt=json

You should now see _fusion_default in the list.

4. Test collection creation

Return to the Fusion UI and attempt to create a collection using the default settings. The collection should now be created without error.

Notes

Note: Ensure these steps are first validated in a development or staging environment before applying in production.

If the script is missing from your environment, or the issue persists after running it, contact the Lucidworks Support Team for further assistance.