Clear Browser Cache and Restart

1. Open Firefox.
2. Click the ☰ menu button in the top-right corner.
3. Click Settings.
4. In the left sidebar, click Privacy & Security.
5. Scroll down to Cookies and Site Data.
6. Click Clear Data…
7. Make sure Cached Web Content is checked.
8. Click Clear.

To restart Firefox:

1. Close all Firefox windows.
2. Open Firefox again from your desktop, taskbar, or Applications folder.