Can't save project preferences in Eclipse

Question

All I am trying to do is to set the Java compiler for my project as 5.0. It is 1.4 by default. When I try to save by pressing OK button I get the following error.

Pr

Answer 1

I had this problem also. I had used two versions of eclipse, one on my home machine (juno) and one on my work machine (indigo). Both shared the same folder using a Dropbox folder. All worked fine until I wanted to make some editor style changes, the settings would not save.

The solution in my case was to update the indigo version to juno on my work machine.