If you experience the above error message on extensions.gnome.org saying that you’re using an outdated version of gnome, try this:
- In a terminal, type firefox -P. This will force it to open the profile chooser. Create a new profile, select it and uncheck “Don’t ask at startup”. Use this firefox window to go to extensions.gnome.org.
- In chrome, you will see a notification asking if you want to allow a plugin to run. Allow it to always run and reload the page. That should get chrome working as well.