Firefox v52+ disables all plugins except for Flash Why do Java, Silverlight, Adobe Acrobat and other plugins no longer work? {web link}

Install Older Version Of Firefox {web link} Be sure to read everything here.

If you still want to downgrade, look under; I still want to downgrade. Click the Directory of other versions and languages link. Look for the directory of the version that you want. But, remember that old versions may have security issues.

You should also check out Firefox; Extended Support Release {web link} ESR Notes System Requirements

Firefox will look for a plugin based on the content-type specified in the page. Normally this is specified in one of two tags:

• <object ... >
• <embed ... >

If you call up the source view of the problem page by pressing Ctrl+u and use Find (Ctrl+f) in that tab, can you find either <object or <embed and see what "type" it specifies?

If neither of those tags is present, close that source view and try the following: select the entire page (Ctrl+a, or right-click a blank area > Select All), then right-click > View Selection Source. That will include not only the original source that you see in the source view, but tags inserted by scripts as the page is loading. Can you find either <object or <embed and see what "type" it specifies?

Note: this forum can go a little crazy with HTML tags in posts. To work around that, you can use &lt; in place of < when Preview Reply indicates a problem.

Actually, if you know the site/device needs its own plugin, can you check whether Firefox knows about its existence. Type or paste about:plugins in the address bar and press Enter to load that internal page. This shows all the plugins Firefox detected on your system (e.g., by checking the Windows registry and its own local folders). Is the one you need listed there?

Please be aware that 64-bit Firefox 52 ESR (and earlier) is locked down to Flash and Silverlight and will not run other plugins. You need 32-bit Firefox 52 ESR to run other plugins.