If you get this error message when protecting files then follow the guidelines below:
- Make sure the actual path+name of the file does not exceed 255 characters;
- Protect the files on a local drive rather than a network one to eliminate any network issues and path names;
- Close down any unnecessary applications to free up available memory.
If the error still occurs and you are protecting a lot of files in one go using command line, then split your files into sub-folders for separate processing.
NOTE
You can get this error in other circumstances as well, when protecting batches of password-protected PDFs, as explained here: https://kb.locklizard.com/knowledge-base/error-message-external-exception-eefface-password-protected-pdfs/.