When I attempt to protect a PDF with password I receive the error "attempt to call a method that has not been implemented" and it does not work. I have attempted a repair as well as removing and re-installing the program. Any other ideas out there? I am using Adobe Acrobat 9.5.5 on Windows 7.
Try a simple password like "admin" and see what happens.
9.x isn't supported anymore, but the feature should certainly work.
Unfortunately, it doesn't even get to where I can type in a password. I click on what I believe is the default "protect with password."
Send a screen shot of what you are clicking on that throws the error.