hi, this is an issue that is caused by one of your extensions (probably grammarly in case you have it present). Disable or remove Add-ons

hi, thanks a lot, my problem was solved by your suggestion.

I have contacted Grammarly to see if there is a solution from their end.

UPDATE: I contacted Grammarly. Please find their reply below.

However, when I deleted Grammarly, I did not have the pesky error. As soon as I reinstalled it per their link below, I had the problem again. It seems evident that the issue is Grammarly - and that they are not taking it too seriously to get this matter resolved.

THEIR REPLY: Thank you for contacting Grammarly Support.

I would suggest you reinstall the extension in order to resolve this issue. It’s a couple of simple steps:

Open your Firefox browser. Click on Tools -> Add-ons -> Extensions. Click Remove to uninstall the plugin. Restart the browser. Download the latest version at https://addons.mozilla.org/en-US/firefox/addon/grammarly-1/

Additionally, we suggest that you please perform an antivirus scan on your computer to make sure that malware is not causing this issue.

I hope this helps, but please feel free to contact me with any questions or comments you might have. We apologize for any inconvenience caused.