Recently I installed Oracle Java. It worked fine, But with the recent upgrade with Firefox throws an error.
I checked it here, which says:
Starting with Firefox Version 52 (released in March 2017), Firefox has
limited support for plug-ins, and therefore will not run Java. Use the
Java Control Panel to find the installed Java version.
I double checked the symbolic link also. It is configured properly
$ java -version
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
How can I run java applets in firefox?
Best Answer
Further commentary from Oracle is linked by the page you quoted, Firefox has taken the explicit decision to stop providing the NPAPI to plugins aside from Flash, essentially meaning, Firefox will not listen to anything Java might try to say.
Your solution then would normally have to be to run Java applets in a browser that allows Java plugins. Try Chromium or QupZilla for example.
If you really want Java in Firefox, you can install Firefox ESR instead. Note that this one will not track regular Firefox version anymore, so your Firefox will grow old feature-wise, but still keep receiving security updates.