Troubleshooting Google Apps Migration for Microsoft Exchange – OAuth Authentication Failure

When trying to use the Google Apps Migration for Microsoft Exchange tool, I came across the following error:

Invalid Consumer Secret specified. Google Apps server has denied access to these credentials.

I checked and double-checked to make sure I had the correct OAuth Domain Key and Consumer Secret entered, and when it still failed, I re-generated the Consumer Secret.  Still no love.  After some searching, I came across this thread on Google’s Product Forums:

Invalid Consumer Secret

In a nutshell, when configuring your OAuth Domain Key, you have the option to “Allow Access to All API’s”.  For, me this box was checked.  Turns out when they say “All API’s”, they didn’t include some new ones that the latest version of the GAMME tool requires.  The tool looks for those API’s, can’t access them with the credentials you’ve supplied it, and falls on its face.  The fix involves you removing that checkmark next to “Allow Access to All API’s” and then heading to the “Manage Third-Party OAuth Client Access” page.  Type in your domain name into the “Client Name” field, and then paste the following into the “One or More API Scopes” field:,,,,,,

Click the “Authorize” button, and that’s that.  Now the GAMME tool completes it’s diagnostic checks and will happily begin migrating the contents of your Exchange mailbox into Google Apps.


8 thoughts on “Troubleshooting Google Apps Migration for Microsoft Exchange – OAuth Authentication Failure

  1. Mike

    Thank you for this. I have just wasted about 3 hours trying to work out what was wrong. Some things Google does are just rubbish. I would be ashamed if my software team had allowed this situation to occur.

  2. Rens van Peer

    KUDOS to you. I had to migrate 200k e-mails from a .pst to Google Apps for Work. I was using GAMMO before, which failed after 200-500 messages. Problems getting GAMME to work, but your solution worked like a charm. I’ve asked my Google case manager to refer to your solution for similar cases.


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