The error “The document “filename.pdf” could not be exported as filename.pdf” started appearing in Safari on attempting to save PDFs from the browser.

The problem appears to be update-related: apparently a recent Acrobat update left an old file in the plugins directory that needs to be deleted.

To fix, go to: 

Macintosh HD/Library/Internet-Plug-Ins/

and drag Adobe PDF Viewer.plugin or any other items that have the letters PDF in the name to the trash.

Quit and restart Safari then test downloading a PDF before emptying the trash.

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