can't upload pdf documents or submit forms

Is this a new problem -- you could previously upload PDFs to websites without problems?

Sometimes Firefox will store a non-default content type for PDFs (such as application/download) and send that to the site instead of the correct type (which is application/pdf). You can correct this by renaming or deleting the settings file that stores these associations and having Firefox regenerate it. Here's how:

Open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Show Folder" button. This should launch a new window listing various files and folders in Windows Explorer.

Leaving that window open, switch back to Firefox and Exit, either:

• "3-bar" menu button > "power" button
• (menu bar) File > Exit

Pause while Firefox finishes its cleanup, then rename mimeTypes.rdf to something like mimeTypes.old

Start Firefox. Can Firefox upload PDFs again?

Note: This process will also have switched your PDF viewer back to the internal viewer if you had customized that, and lost your preferred email link handler, if you had set that. You can restore those settings on the Options page if necessary:

• View and edit PDF files using Firefox’s built-in viewer
• Change the program used to open email links

Thanks you for the quick reply. Yes, these are new problems. Your description of the PDF upload issue sounds correct (the file wasn't recognized as a PDF file type by the website), so I performed the steps you outlined and I will try it in a few days when I need to upload another PDF to the same website. I'll let you know if that fixed it.

The bigger problem is the form submittal issue. On E*TRADE, I filled in a web form in Firefox, clicked Submit, then nothing happened and the same page simply refreshed. E*TRADE suggested I use a different browser, so I tried Edge, repeated the same entries, clicked Submit, and the form was submitted successfully.

With Credit One Bank, the web form was an attempt to reset the password on my account... after clicking Submit in Firefox, the screen said it was successful but the new password didn't work. Credit One wanted me to switch to Chrome, which I refuse to do. I tried Edge hoping to repeat my E*TRADE experience, but Edge didn't work either. I'm going to submit that particular issue to Credit One's tech support folks. Apparently they work for Google.

For the form submission issue, three thoughts:

Tracking Protection

Firefox now blocks some content in private windows, which may include external components of websites. If you check the left end of the address bar, a "shield" icon should appear when tracking protection is being applied. This article has more information on making site-specific exceptions or turning it off and on as needed: What happened to Tracking Protection?.

Cache and Cookies

When you have a problem with one particular site that previously worked normally, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.

(1) Clear Firefox's Cache

See: How to clear the Firefox cache

If you have a large hard drive, this might take a few minutes. If you do not see the number going down on the page, you can reload it using Ctrl+r to check progress.

(2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either:

• right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Cookies"
• (menu bar) Tools > Page Info > Security > "View Cookies"
• click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button

In the dialog that opens, the current site should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually.

Then try reloading the page. Does that help?

Extensions, Customizations, Advanced Features

If the above doesn't help, could you test in Firefox's Safe Mode? In Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem.

If Firefox is not running: Hold down the Shift key when starting Firefox.

If Firefox is running: You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

and OK the restart.

Both scenarios: A small dialog should appear. Click "Start in Safe Mode" (not Refresh).

Any improvement?

Hmm, one other thing: if you have modified your cookie permission settings (for example, blocking third party cookies) or local storage/DOM storage settings, those can cause subtle failures that websites might not properly warn you about. There could be changes that you made personally, or that a privacy-oriented add-on might have made without clearly explaining what it did...

These are good suggestions... thank you. I always cringe when someone says "clear your cookies" because you lose all your site settings for all sites. But you describe a process where I can clear cookies for just one site... I didn't know that was possible. I will try these suggestions when I need to access those sites again, or if I run into the same problems elsewhere. Thanks again!