Another user reported an issue pasting on YouTube yesterday ([https://support.mozilla.org/en-US/questions/1219577 1219577]). Does it matter what method of pasting you use? For example: * Ctrl+v or Ctrl+Insert * right-click > Paste * (tap Alt to activate menu bar) Edit > Paste Does it matter whether you first type a character or two in the comment box before trying to paste? ---- If a site is generally known to work in Firefox, these are general suggestions to try when it stops working normally: '''Cache and Cookies:''' When you have a problem with one particular site, 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. (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? '''Double-check content blockers:''' Firefox's Tracking Protection feature and extensions that counter ads and tracking may break websites that weren't built to operate normally without the blocked components. Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the Tracking Protection feature in this article: [[Tracking Protection]]. Extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site. '''Testing in Firefox's Safe Mode:''' In its 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. (On Mac, hold down the option/alt key instead of the Shift key.) ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" Help > Restart with Add-ons Disabled * (menu bar) 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?