We built a design system for an injury rehab app, and the error messages were more painful than the recovery. | Design System Stories - The Design Community Hub
Inline validation errors are honestly the best part of a good design system. If your rehab app is telling people they typed their birth year wrong before they submit, that's a win. A bad system would let them get all the way through and then just say "form error". Sounds like the team maybe missed the point of helpful messaging.
My buddy Jake spent 45 minutes on a permit site last week. He uploaded all his PDFs, typed in his parcel number, hit submit, and it just said "upload failed." No clue which file or why. @angelaprice is right, that vague stuff kills you. A simple note like "file too large" right under the upload box would have saved his whole afternoon. He had to guess and shrink each file one by one.