Could you describe the steps in your workflow? For example:

(1) Open the PDF from the website in Firefox's PDF viewer

Question: is it an https:// address or a file:/// address in the address bar for the PDF viewer?

(2) Fill the form

(3) Save the updated form using one of these methods:

• The Download/Save button next to the Print button on the PDF viewer's toolbar
• Ctrl+S or "Save page as..." from the menu
• Print to PDF using one of the various Destination options

(I don't recommend the third one.)

1) I open the form from a folder on my computer with Firefox (file address). 2) I fill the form. 3) I save the form via the download button in the browser or ctrl+S.

After that, I can ONLY see what I've written in the pdf if I use Firefox. The fields are simply empty in Adobe Reader, or when I print. This is true on two computers, a Win10 machine and a Mac, so I presume it's true on all computers.

I don't think Firefox actually edits the original file. When you save, are you overwriting the original file or saving with a new name or in a new location?

I give it a new name and save it in another folder (though I have tried overwriting THAT file a few times). As mentioned, Firefox can still open the pdf will all the information I entered into it - it's just that I can't print it or open it in Adobe.

My guess would be that there is something special about the forms that Firefox is breaking. Whether that involves a security setting, or some kind of layering, I don't know.

Is it a public form you can link to? When posting a link to a non-Mozilla site, please put a space before the top level domain to bypass the spam link moderation queue:

https://www.example .com/etc

Sure, here's the link: https://www.irs .gov/pub/irs-pdf/f1040.pdf

It's not just this form, though, it's ALL the IRS forms that appear to have this problem. I download them, move them into their folder, then open them from that folder.

I just tested with two name fields and one checkbox, and those worked. Maybe the issue is with other types of fields.

Yes, please try the lower fields. Those are the main problem.

I filled some number fields randomly, but cannot replicate the problem. Seems for now you should just use Acrobat for this.

This is so strange... ah well. Thank you for looking at it.