The reason is that the new version has changed the file structures and didn't provide the coresponding convension tools. So here is endly the solution:
- Backup the whole workspace before upgrading;
- You can enable or disable a new version jBPM plugin under "help"->"software updates"->"manage configurations";
- After the new version is running, create a blank process project, then create a blank process definition;
- Close eclipse, find the folder where the new created process files are;
- Open gpd.xml and processdefiniton.xml of the new process and your old process in an editor;
- Just compare the difference between those files. Mostly the new version of jBPM changes the structure of gpd.xml;
- So change the xml structure manually and save them;
- Maybe the file .classpath should alse be compared and changed.
- Open it in eclipse. If you are lucky, you will never see the error message again.