Is this on every web page, many, some?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. Is the problem still there?

How about on this test page: https://jsfiddle.net/5yosxudf/

Can you link to one or two pages that have this problem so we can check whether a custom CSS rule or script is blocking pasting in those fields?

Also, if you do not want sites to be able to block the right-click context menu, you can change a setting here:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste contex and pause while the list is filtered

(3) Double-click the dom.event.contextmenu.enabled preference to switch it from true to false

After this change, Firefox's context menu will sometimes appear in front of a site's own context menu. To clear Firefox's menu so you can access the site's menu, press and release the Alt key. (Pressing Esc sometimes clears just Firefox's menu, but may also clear both menus.)

jscher2000 said

How about on this test page: https://jsfiddle.net/5yosxudf/ Can you link to one or two pages that have this problem so we can check whether a custom CSS rule or script is blocking pasting in those fields?

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Also, if you do not want sites to be able to block the right-click context menu, you can change a setting here:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button promising to be careful.

(2) In the search box above the list, type or paste contex and pause while the list is filtered

(3) Double-click the dom.event.contextmenu.enabled preference to switch it from true to false

After this change, Firefox's context menu will sometimes appear in front of a site's own context menu. To clear Firefox's menu so you can access the site's menu, press and release the Alt key. (Pressing Esc sometimes clears just Firefox's menu, but may also clear both menus.)

Hi: Thank you very much for your answer!

I used your test page and it worked fine with Ctrl+V

After changing the dom.event.contextmenu.enabled preference I could use the firefox right-click context menu and I could copy, but Ctrl+V doesn't work

Try the Insert key versions to see if they work.

Use keyboard shortcuts if the buttons on the web page 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)