Hello,
We have been migrating several projects from our on-premise Jira server to the cloud instance successfully over the last weeks.
Today when I go to migrate 1 project to our production site I get the following reported:

Note! When I try this on my sandbox site it works fine
The Jira server application logs these errors related to pre-flight:
Pre-flight execution .... (4-5 of them)
Caused by: com.atlassian.jira.migration.httpclient.exceptions.UnexpectedStatusCodeException: Received an unexpected status code; expected [200], but received 401: {"code":401,"message":"Unauthorized"}
Any pointers to figure this out would be greatly appreciated.
Thank you
Atle