Can't edit my records

Can't edit my records

It's no problem to add new records, but if I want to edit any of the existing records I always get the message:
"Invalid entries found. Please correct and submit again".

When I view the error details, following message is shown:
" Error at on update script.
Note: We are working on giving more meaningful error messages on script failures"

So I thought there must be a problem with the scripts. I deleted all scripts and tried again.
After that, the message changed to: "Illegal pattern character 'n'" and no data was stored.

So, at the moment, I can't use my application, because no record can be edited.

What can be the reason for this error which appeared without any changes from our side at the application?

Thanks for helping.
Wolfgang