Lotus Notes Troubleshooting : Error message "File does not exist"

This error occurs due to user enabled the option "Automatically append a signature to the bottom of my outgoing mail messages" in the Tools > Preferences where the mail signature file was not found.

Solution 1 - Disable the signature:
Go to More > Preferences > Mail > Signature > uncheck "Automatically append a signature to the bottom of my outgoing mail messages" > press OK

Solution 2 - Relocating the signature file:
Go to More > Preferences > Mail > Signature > Select HTML or Image File > Browse and choose your signature file > press OK