Attacment in plugin revision document

Hello, please I really need help.
Enjoyed the plugin and it works fine, but I have the plugin wp document revision and the type of post is document.
Already activated the option to allow attachment to the document type, but when I try to upold the error arises

Unexpected error occured. Please refresh the page and try again.

I do not understand how I can solve the problem and would like help.

Thank you.