Jira Cloud Migration Assistant fail to migrate project due to Reference [Group_Name] is not a group reference.
Problem
When exporting a project from your Jira server to Jira Cloud using the Jira Cloud Migration Assistant the project migration will fail and the following ERROR will appear at the migration logs:
TEST.log:2020-07-27 06:59:08.282 ERROR TEST project-export We couldn't export Project Role 'Administrators'. Reason: java.lang.IllegalArgumentException: Reference "project_admin" is not a group reference.
TEST.log:2020-07-27 06:59:08.283 ERROR TEST project-export We couldn't export Project Role 'Users'. Reason: java.lang.IllegalArgumentException: Reference "jira-users" is not a group reference.
TEST.log:2020-07-27 06:59:08.352 ERROR TEST project-export We couldn't export Project Role Association 10011. Reason: java.lang.IllegalArgumentException: Reference "project_admin" is not a group reference.
TEST.log:2020-07-27 06:59:08.355 ERROR TEST project-export We couldn't export Project Role Association 10019. Reason: java.lang.IllegalArgumentException: Reference "jira-users" is not a group reference.
Cause
These Errors will occur when one or more user groups that no longer exist are listed as a project role or on the project's permission scheme.
Resolution
There are two possible solutions for this issue:
1) Re-create the missing groups so that they exist on the Source server before running the migration again.
2) Edit the project's roles and permissions to remove any references to these groups before running the migration again.