If you started getting the error “This application does not exist” after you started using OAuth to authenticate and upload your application, This is the solution.
Cause – Its only saving the OAuth token for a single account. So if you like me is using multiple app engine accounts you might want to follow this instructions.
App engine launcher saves the OAuth token on your home folder and its named –
You need to find and delete this file. On windows machines it will be under C:\Users\admin or C:\Users\[Username]