Try keyboard shortcuts in case the buttons on the webpage or other methods aren't working.

• Copy: Ctrl+C or Ctrl+Insert (Mac: Command+C)
• Paste: Ctrl+V or Shift+Insert (Mac: Command+V)
• Cut: Ctrl+X or Shift+Delete (Mac: Command+X)

Cor-el, I tried the keyboard shortcuts and they don't work in Firefox.

To be clear, the keyboard shortcuts do work if I'm copying and pasting within the same document. But not in the situation as I've described: from one document to another.

Are the documents open in two different tabs in the same window? I cannot replicate the problem in that scenario. Can you confirm that the source text was copied to the Windows clipboard by pasting outside of Firefox, for example, into Notepad?

Are the documents open in two different tabs in the same window? I cannot replicate the problem in that scenario. Can you confirm that the source text was copied to the Windows clipboard by pasting outside of Firefox, for example, into Notepad?

Yes, two different tabs in the same Firefox window. I'm back at home where I use Linux. In Firefox Linux, I can't replicate the problem. Next week, I can access the same Windows machines again and I can try to replicate the problem.

Works for me. see screenshot What version of Windows? Did you try in Safe Mode? https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode#w_how-to-start-firefox-in-4troubleshoot-modesf5safe-modesf

I just tried again on the same windows computers and copy and paste does not work on firefox windows.

jonzn4suse, Windows 7 Pro, Service Pack 1.

I just tried copying and pasting in the same document and even that doesn't work. This is bonkers.

Did you test whether the text is on the Windows clipboard by trying to paste outside of Firefox?

Are you using containers in case this makes a difference ?

• https://support.mozilla.org/en-US/kb/containers

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Hi Cor-el, I have the containers extension (One huge reason why I love firefox!), but I'm not using containers in this situation.

I started FFox in Troubleshoot mode. I did not see a "Refresh Firefox" button when I went thru the process to start Troubleshoot mode. All I saw was a message saying something like "All your extensions have been disabled", and the only button was an "OK" button, which I clicked.

I disabled the dark theme.

Copy-pasting in the same Google Document still does'nt work. But copy pasting this reply message in this support.mozilla.org page still works. But copy pasting this reply message in this support.mozilla.org page still works. But copy pasting this reply message in this support.mozilla.org page still works. (there... i copy-pasted twice :) )

Finally found an answer!

This comment on another post solved my problem:

In about:config, set dom.event.clipboardevents.enabled back to true.