I use a 3rd party certificate (Entrust) to digitally sign plans. After selecting digitally sign using Certificates under Tools, I am able to drag the signature box and choose where to save. Once save is clicked and the digital signature is generated, the file will freeze, abruptly close, and/or get the below warning. It should be noted that the signed file still gets saved/created and upon re-opening, diplays everything correctly with the signature. I am trying to determine what causes the crash. It appears to occur when Adobe regenerates the file after the signature is applied. I have found similar posts but nothing exactly like this.
Crash or freeze
Security digital signatures and esignatures
Hope you are doing well and sorry for the trouble.
Is this an issue with the specific PDF file signed by the 3rd party certificate (Entrust) or with other PDF files as well? Please try to sign a different PDF file with a different / verified certificate and see if the issue still occurs?
Also make sure you have the recent version 22.1.20117 (Win), 20112 (Mac) of the application installed. Go to Help > Check for updates and reboot the computer once.