Description of problem:

The currently displayed error messages on the /catalog-import are not sufficient enough to help users troubleshoot issues with their entity files.

For example, user tried to register an entity file with an invalid "metadata.name" value. All that's displayed in the UI is the "Request failed with 400" message. However, when I check the catalog API response in the network tab, the error message clearly says what's wrong with the file (see screenshot).

I've personally seen a similar situation happen quite a few times already. Users usually reach out to us for support since they don't open the browser network tab to see what's wrong and they shouldn't have to.

Prerequisites (if any, like setup, operators/versions):{}

None

Steps to Reproduce

Go to "Self-service" page, click on "Import an existing Git Repository" and try to import an invalid entity file.

Actual results:

"Request failed with 400" message is displayed.

Expected results:

Actual error message that's returned by the catalog API should be displayed, providing users with more details around the error.

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

RHDH Metadata RHDH Version: 1.7.2
Backstage Version: 1.39.1
Upstream: https://github.com/redhat-developer/rhdh/tree/release-1.7 @ 683f6a4e
Midstream: https://gitlab.cee.redhat.com/rhidp/rhdh/-/commits/rhdh-1.7-rhel-9 @ 4ec86f43
Build Time: 2025-10-29T18:30:03Z

Additional info (Such as Logs, Screenshots, etc):

See attached screenshots and Slack discussion.