The use of an older version of Firefox most likely causes this issue. Before continuing to the solution steps, upgrade to the latest version of Firefox and try to access the web UI again. If the upgrade does not resolve the issue:
- Reload the webpage and bypass the cache to refresh possibly outdated or corrupted files:
On a Windows system: Hold down the Shift key and left-click the Reload button.
On Windows or Linux: Press Ctrl + F5 or Ctrl + Shift + R
On a Mac: Press Command + Shift + R
- Clear the cache and remove cookies from websites that cause problems:
Clear the cache:
- In Firefox, click Tools, Options, Advanced, Network, Cached Web content.
- Click Clear Now.
Clear Cookies:
- In Firefox, click Tools, Options, Privacy, Use custom settings for History.
- Under Cookies select Show Cookies.
- Clear any cookies for affected websites.
- Start Firefox in Safe Mode to verify if one of the active extensions, or hardware acceleration, could be causing the problem:
- In Firefox, click Tools, Add-ons, Extensions.
- Disable extensions and hardware acceleration and retry.
