If you encounter this error message when opening a pdf in your web browser (Chrome, Firefox, Edge, etc.) please do the following:
- Download the pdf. (Look for the download option in the top left of your browser.)
- Open your Downloads folder.
- Open the pdf you just downloaded, using Adobe Acrobat.
If double-clicking on the pdf opens it in your browser instead, right-click on the pdf and select 'Open With > Adobe Acrobat Reader'.
This error message occurs because the file you are trying to view was created using a defunct pdf editor program, which modern web browsers no longer support. However, the old pdf format should still be readable by Adobe Acrobat.