Could be a error in your script - the path used in your script could be incorrect. You would need to post a copy of the script that you are using on this forum.
9 times out of 10 or more, the issue is with an invalid path used in the save as PDF step--ironically, the one cause not mentioned clearly in the error message that FileMaker displays when this happens.
You may find this thread on use of a $path variable helpful: Exploring the use of a $Path Variable in Scripts
Thank you so much for your prompt and perfectly specific reply. My issue turned out to be "filemac" at the beginning of the path. Somewhere along the line, either MacOSX or FMP changed that requirement for me. The FM help seems to indicate that "file" will suffice cross platform, but apparently not.
Again, thank you so much!
"file:" should work as the start of your file path. "File:" however, will not as this tag is apparently case sensitive.