On Bitbucket server 4.14.4 as a system administrator:
- Go to profile
- Click "Import repository"
- Import from Bitbucket Cloud
- Enter username (tried both legacy username and email address)
- Generate and enter an App password
- Click "Connect"
A popup then appears with the title "An error occurred" and the content"
"Something went wrong while trying to serve your request. Try reloading the page."
After reloading the same error occurs.
I have tried with Firefox and Chromium, both with adblock disabled.