During a large cPanel migration test, the upload finished and the page then came back blank, with no error and no new account.
What happened
The new upload progress overlay finished the request in the background, and the browser followed the redirect automatically. The page then navigated to the same address a second time, and by then the one-time validation message had already been consumed, so a pristine form was shown.
The fix
The completion handler now renders the response it already received instead of requesting the page again, so errors and resubmitted values are shown. We verified it with a deliberately invalid archive: the validation message now appears where it should.
Cleanup
While checking that a failed import leaves nothing behind, we found the cleanup only handled one class of error. It now handles any unexpected failure, matching the other import paths.
Full suite (2572/2572) and pint --test before shipping.