hello madipiller, maybe see PDF files are blank or cause an error message on Mac & What to do if you can't download or save files.

Is your question about Mac or Windows??

On the Mac, many users have to disable the Adobe Acrobat plugin to solve the blank page problem. You can do that here:

Tools > Add-ons > Plugins category

If Firefox can't figure out to launch PDF forms in Preview, you can educate it here:

Firefox > Preferences > Applications

In the slim search box above the list, type or paste PDF, then pause while Firefox filters the list. You should be able to update the program to handle the PDF using the drop-down list in the right column of the list.

Not sure about the Word documents. If you search the Application preferences in that same dialog for Word or DOC, can you figure out how Firefox is trying to open them?

Thanks a lot The Firefox > preferences > Applications worked perfect ! I typed PDF and indicated to be read by Adobe Acrobat Reader Thanks