Hello,

Try Firefox Safe Mode to see if the problem goes away. Firefox Safe Mode is a troubleshooting mode that temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes).

If Firefox is open, you can restart in Firefox Safe Mode from the Help menu:

• Click the menu button , click Help and select Restart with Add-ons Disabled.

If Firefox is not running, you can start Firefox in Safe Mode as follows:

• On Windows: Hold the Shift key when you open the Firefox desktop or Start menu shortcut.
• On Mac: Hold the option key while starting Firefox.
• On Linux: Quit Firefox, go to your Terminal and run firefox -safe-mode
  (you may need to specify the Firefox installation path e.g. /usr/lib/firefox)

When the Firefox Safe Mode window appears, select "Start in Safe Mode".

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article to find the cause.

To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

Try accessing the Docs with Safe mode on to see if it works.

When you figure out what's causing your issues, please let us know. It might help others with the same problem.

в безопасном режиме все заработало.

Как понять, какое дополнение вызывает ошибку? только перебирать ?

in safe mode, everything worked.

How do I know which add-on is causing the error? just iterate over?

Glad to hear that everything works in safe mode.

If you have any ad blockers like ublock origin or script blockers installed, try adding Google docs to the exception as the plugins could be blocking site functionality.

If you have cookie protection setting on to block "All Cookies", try reducing the protection level or Websites say cookies are blocked - Unblock them add an the sites as exceptions and try again.

If those steps don't work, follow the steps in this guide

Yes, you can follow this section in the troubleshooting guide.

Also check whether you have any "user agent switcher" type extensions.