Google App Engine rollback

Unable to update app: Error posting to URL: https://appengine.google.com/api/appversion/create?app_id=xxxxx&version=1&
409 Conflict
Another transaction by user xxxxxx is already in progress for app: 
xxxxx, version: 1. That user can undo the transaction with "appcfg rollback".

If you get this error which is usually due to a previously interrupted deployment process

Navigate to your app engine sdk folder and then the bin folder.
Execute the command appcfg.sh rollback "Your application Path/war/WEB-INF"
You will need to supply your google email and password and this is the tricky part. If your login information is rejected, you need to go to your google account security settings and "enable for less secure apps", and try again.