in Google App Engine, GWT

How to rollback a transaction in GAE

This has nothing to do with JPA.
I was trying to deploy a GWT webapp to GAE when I suddenly got an error.
As a remedy, i got the message :
" Error posting to URL:
409 Conflict
Another transaction by user xxxxx is already in progress for this app and major version. That user can undo the transaction with's "rollback" command."

After digging into Google a bit, I found that the way to launch that rollback command under Windows is the following :
1) Figure out where the Google App Engine Java SDK directory is.
In my case, it’s under the Eclipse plugins directory :

The bin folder contains the appcfg.cmd command.

2) Under a DOS command prompt, go to the workspace folder of your project and launch the following command :
"D:\Dev\eclipse-jee-helios-SR1-win32\plugins\\appengine-java-sdk-1.4.2\bin\appcfg" rollback war

After that, you can try to deploy the app again and it should work.

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