When editing artist credits of a relationship from the URL editing page - see comment to Tidal's ticket for example - or any other attribute of such relationship (begin date, end date, ended flag), an error will be legitimately thrown if the URL does not follow the normalized form. The message "This URL is [not allowed for the selected type, or] is incorrectly formatted." is correct but not explanatory enough about how to fix it. This message will improve over time, but fixing will still not be straightforward.

An improvement over this would be to systematically suggest normalizing the URL through a simple button under the "URL" field in the URL editing page if the URL is not "clean".