Hi everyone,

I have a strange issue with the Umbraco instance noticed in the latest weeks:

When I save a document, I get the following error in a popup:

looking in Network, it seems that the PostSave call is returning 500 HTML error code but without any detail (hence the empty popup):

Background:

• to try to resolve the issue I've upgraded the Umbraco instance to the latest version: 8.9.1
• I don't get anything in the Logs, only some weird warnings with Umbraco not being able to do some checks:

• there is no other error, etc
• there is only one installed package:
• we have FullTextSearch package installed, upgraded to the latest version, v1.0.0: https://our.umbraco.com/packages/website-utilities/full-text-search-8/
• I've gone through all datatypes and they all seem to be ok
• gone through all document types and saved each, seem ok
• with a backup database I've deleted all the properties from a document (there were only two default properties left) and when saving the empty document the same error appears
• even though the error appears, the document is saved ok, so the problem is not important or urgent, but it's frustrating and annoying
• when clicking on Settings in the top navigation, there is the following error in the browser console (I've tried to "debug" the javascript files but without luck. It seems like a bad data type or document type):

I've spent many hours trying to clean up the Umbraco instance, to understand the cause for this, any idea of what I could try would be very appreciated.

Many thanks!