My script cannot find the SetaPDF class... why?

If an error message like:

Fatal error: Class 'SetaPDF' not found

appears in all likelihood you simply had created an own file named SetaPDF.php (maybee for testing purpose) in any path of your current include_path.

Because each API does a require_once on SetaPDF.php PHP didn't load the original setapdf.php but tries to include your own defined file.

The following message can appear for the same reason:

Fatal error: SetaPDF core with at least version X.X is needed! You should update your files!

Also if you're already using the newest files.

Avoid naming your files the same
as a file of any SetaPDF API