Issue Summary

When the source and destination sites have a large number of groups (>10,000), the "Groups with the same names exist on the destination" preflight check returns an unexpected error instead of completing successfully.
 

Steps to Reproduce

1. Have >10,000 groups on the source/destination site
2. Attempt to migrate Jira/Confluence space from Site A to Site B within the org

Expected Results

When group name conflicts are detected, the check should complete and present the following options:

1. A button to download the CSV file of conflicting groups
2. A button to merge the conflicting groups
   

Green light to proceed the migration, after clicking on "Merge groups" button:

Actual Results

From the logs, the check continues and completed. But UI shows the check fails with the following unexpected error:

We found an unexpected error and couldn't run this check. Try validating again or contact support if you continue to get this message

Unable to proceed the migration because "Merge groups" button is not selected.

Workaround

Contact Atlassian Support to get the list of duplicate groups and trigger "Merge groups" option.