"Failed to add data" error message in multiple apps

"Failed to add data" error message in multiple apps

Hi

I have just logged this issue with Zoho support (with access to an app enabled), but getting "Failed to add data" error message in multiple apps when trying to add data in a form submit.  The apps have worked for several years and nothing has been recently changed.  I deleted some old data to make sure records limits are not being exceeded, and the setup usage limits are all ok.

Anyone else getting this issue or any ideas?  Apps are not usable, so hoping to get this issue resolved asap