Q:

Google App Engine fails to deploy with message "Version not ready"

I use Eclipse to deploy my java code to Google App Engine.  But over the past two weeks I found that it very often hangs at "Verifying availability" of the frontend.  After waiting for a long time with a bunch of "Will check again in 60 seconds", the deploy fails.  Through trial and error, I also found out if I delete the backend or sometimes delete the version completely and do a deploy again, it is more likely to succeed.  Below is the error message:
Unable to update:
java.lang. RuntimeException: Version not ready. 
at com.google.appengine.tools.admin. AppVersionUpload.commit(AppVersionUpload.java:572)
at com.google.appengine.tools.admin. AppVersionUpload.doUpload(AppVersionUpload.java:143)
at com.google.appengine.tools.admin. AppAdminImpl.doUpdate(AppAdminImpl.java:328)
at com.google.appengine.tools.admin. AppAdminImpl.update(AppAdminImpl.java:52)
at com.google.appengine.eclipse.core.proxy. AppEngineBridgeImpl.deploy(AppEngineBridgeImpl.java:433)
at com.google.appengine.eclipse.core.deploy. DeployProjectJob.runInWorkspace(DeployProjectJob.java:148)
at org.eclipse.core.internal.resources. InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs. Worker.run(Worker.java:54)

Thanks in advance. 

A:

I use GAE Python.  When I have problems with deploying an application I have to rollback first in order to deploy the application again.  Sometimes deploying fails (in the way you describe) during maintance hours by the app engine team.  To solve this, I had to wait a couple of hours. 