Error while compiling classes using Intellij 5.1.1 + jdk 1.3.1

I just upgraded from IntelliJ 5.0 to 5.1 and now I get:

Error: Bad class file format: 31
Error: Bad class file format: 16

I have tried rebuilding, changing java versions... nothing has worked.

1) Check that your JVM settings are set to the right jvm.

2) Check that IntelliJ is running with the latest VM on your pc or the one it (IJ) came with.

3) Try wiping your output folder where class files go (Idea will create a whole new one). Perhaps they have changed something in the format.

The java compiler version in my project is 1.5.0_07 b3.
The bundled IntelliJ java version is 1.5.0_07 b3.

I have followed all your steps and I am unable to fix this either. If I hit compile twice it goes away, but as soon as I make a change and recompile it is back....

I even gave 5.1.2 a try.

I upgraded to Intellij 5.1.2 and now I am able to compile all class well.

I'm yet another victim. I have tried

-updating to intellij 5.1.2
-reconfiguring the jdk options of my project
-reinstalling jdk1.5 (my sources are only compatible to jdk1.5)
-deleting all classes (the worst case, i had to re-make my project dozens of times)
-deleting the cache files of intellij in my home dir

NONE OF THESE WORKED!

Check file types in intellij settings - I had a blank line under Java class files. When removed that then everything worked just fine.

Thanks A LOT!!! You did it; I couldn't resolved this issue for a long time, thanks!

Wow, this fix worked for me too. I'm not sure how a blank filetype showed up here, but it sure did. FWIW, I was running IntelliJ 5.1.2 and JDK 1.4.x, so I'm guessing it's more of an IDEA issue than a JDK one.

Thanks for posting it! Not sure how I'd find that on my own.

Worked for me, too! Thanks a lot!