I have installed java and firefox.

root@localhost:/home/debian# java -version
java version "1.8.0_45"
Java(TM) SE Runtime Environment (build 1.8.0_45-b14)
Java HotSpot(TM) Server VM (build 25.45-b02, mixed mode)

And link libnpjp2.so into firefox plugins directory.

ln  -s  /usr/lib/jvm/java-8-oracle/jre/lib/i386/libnpjp2.so    /usr/lib/mozilla/plugins/libnpjp2.so

Strange things happened in my pc that in my console:

1.when to input firefox http://java.com/en/download/testjava.jsp with root ,

A newer version of Java is available
Please click the download button to get the recommended Java for your computer.
Your Java version: Version 8 Update 45

2.when to input firefox http://java.com/en/download/testjava.jsp with normal user ,

Verify Java Version
We are unable to verify if Java is currently installed and enabled in your browser.

3.There is no java plugin displayed when to input about:plugins in my firefox.

enter image description here How to set java plugin properly in my firefox ?

  • is there also a /usr/lib64/mozilla/plugins/ directory?
    – ILMostro_7
    Jul 16, 2015 at 7:39

1 Answer 1


Your user's profile isn't in /usr/lib/mozilla/ but in /home/user/.mozilla/; therefore, you have to link the java plugin to there

ln -s /usr/lib/jvm/java-8-oracle/jre/lib/i386/libnpjp2.so /home/user/.mozilla/plugins/

Take a look at this mozilla support thread for some possible hints/alternative options.

As an alternative, install the icedtea plugin instead of the oracle browser plugin.

Also, check to make sure your java installation and your firefox package have the same architecture; i.e. 32-bit vs. 64-bit. Therefore, you might need to create the link in the /usr/lib64/mozilla/plugins/ directory, if it exists.

Finally, try deleting the pluginreg.dat file in your profile directory:

rm -rf ~/.mozilla/firefox/some_weird_name.default/pluginreg.dat

This file will be recreated the next time you start firefox.

  • It is no use ln -s /usr/lib/jvm/java-8-oracle/jre/lib/i386/libnpjp2.so /home/debian/.mozilla/plugins/libnpjp2.so
    – showkey
    Jul 16, 2015 at 6:41
  • then just stick with the icedtea plugin; not sure why you would absolutely NEED the oracle java plugin instead.
    – ILMostro_7
    Jul 16, 2015 at 7:27

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