User migration step failure with error code 403

Issue Summary

User migration step failed intermittently with

Caused by: com.atlassian.jira.migration.httpclient.exceptions.UnexpectedStatusCodeException: Received an unexpected status code; expected [200], but received 403: 

Steps to Reproduce

1. Step 1
   When you select scoped user migration for significantly large projects.
2. Step 2

Expected Results

User migration finished successfully.

Actual Results

Failed with

com.atlassian.jira.migration.httpclient.exceptions.UnexpectedStatusCodeException: Received an unexpected status code; expected [200], but received 403: *strong text*

The above exception is thrown in the Jira log file:

...

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available