java.lang.UnsupportedClassVersionError

I compiled a few java classes with Eclipse and uploaded on Google App Engine. It didn’t work.

In the logs, it shows:

java.lang.UnsupportedClassVersionError …. minor 51

I googled on the Internet. Someone said:

It means that you compiled your classes under a specific JDK, but then try to run them under older version of JDK.

It spent me quite a lot of time to fix it.

Google App Engine said it supported Java 5 or 6, in other words, jdk1.5.0 or jdk1.6.0.

I added java path to the .ini file. Nothing changed. I think, this step is useless.

On Eclipse, on Windows->Preference. Click “compiler” to open the window, change JDK to 1.6. And JRE’s directory pointed to the JRE6.

It didn’t work. Later on, I found on the windown above, there is a link to remind me to change the JDK of my Application. I did it. Then it works.:))