New versions of the Firefox web browser occasionally will not print or display pdf files correctly,
New versions of Firefox uses it own pdf previewer to display and print pdf files. In some cases the previewer does not print or display pdf files properly. Firefox developers are aware of this issue and are working to resolve this.
If you are having difficulties viewing or printing a pdf file with Firefox and its default previewer; it is possible to configure Firefox to use the Acrobat player program to view these files.
If you do not have Adobe’s Acrobat Reader program installed on your computer it can be downloaded from here.
This video shows how to set Firefox to use Acrobat Reader view pdf files.