error running builder in GaeNature, Google App Engine in Eclipse

Question

I get an intermittent error when launching Eclipse with an open GAE project. It prevents me from building my project. I can sometimes get it to clear by deleting the contents of the "war/WEB-INF/classes" folder and then restarting Eclipse. Sometimes I close the project, close eclipse, launch eclipse, open the project and that seems to help. The error has been happening for several months and has persisted through a GAE plugin upgrade. I can usually get Eclipse to work eventually. Once it works it keeps working great until I relaunch it.

I am using GAE appengine-java-sdk-1.6.3 GWT 2.4.0 Objectify 3.1 (love it) Eclipse Indigo SR2 Windows 7 64-bit

It feels like maybe a race condition when starting Eclipse.

Any ideas?

These errors occur during the build ======================

Errors running builder 'Java Builder' on project '*'. com/google/appengine/eclipse/core/nature/GaeNature

Errors running builder 'Google WebApp Project Validator' on project '*'. java.lang.NullPointerException

Error instantiating builder 'com.google.appengine.eclipse.core.projectValidator'.

Plug-in com.google.appengine.eclipse.core was unable to load class com.google.appengine.eclipse.core.validators.GaeProjectValidator.

An error occurred while automatically activating bundle com.google.appengine.eclipse.core (841).

Plug-in com.google.appengine.eclipse.core was unable to load class com.google.appengine.eclipse.core.validators.GaeProjectValidator.

An error occurred while automatically activating bundle com.google.appengine.eclipse.core (841).

===================

I also got this error when trying to open the Google/App Engine properties dialog in Eclipse

Unable to create the selected property page. An error occurred while automatically activating bundle com.google.appengine.eclipse.core (841).

I have found that if I disable "Build Automatically" from the Project menu before I exit Eclipse then it will come up OK the next time. I can then turn on "Build Automatically" after the launch has completed. This happened 3-4 times. This supports the idea that there is a race condition between Eclipse launching and building the project. But because the problem is intermittent, it might just be a coincidence. — philburk

zovits zovits · Accepted Answer · 2012-04-11T08:28:30

I have also encountered this error today. First I checked the project's properties to see if anything was out of place, but the Google App Engine tab wouldn't even open properly. It only gave a not-too-helpful error message: Unable to create the selected property page. An error occurred while automatically activating bundle com.google.appengine.eclipse.core (7).

After this I tried uninstalling and reinstalling the Google App Engine SDK, and after restarting Eclipse the GAE worked just like it was supposed to.

error running builder in GaeNature, Google App Engine in Eclipse

2 Answers