Sign in with Google Outlook Sync Authorization Error 400 Invalid Request

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Authorization Error - Error 400: invalid_request

You can’t sign in to this app because it doesn’t comply with Google’s OAuth 2.0 policy for keeping apps secure.

You can let the app developer know that this app doesn’t comply with one or more Google validation rules.

Google has changed the OAuth Process. Current releases of CompanionLink are fully compliant. If you see this error, you just need to update to the current version. To do this - in CompanionLink - go to Check for Updates, and let the software update.

Google is deprecating the OAuth Out-of-Band (OOB) flow. This has been the method that PC Apps use to request OAuth tokens. An OAuth token is the result of the "This App want to access" screen that shows Contacts and Calendar for Outlook Sync tools.

You will need CompanionLink Version 9 (build 9070) or CompanionLink Version 10 (build 10014 or higher) If you already own CompanionLink v9 or higher then this is a free update. If your license is for CompanionLink Version 8 (before August 1st 2018) or older, you will need to purchase an upgrade here.


To help protect your account, Google will soon block apps that don't comply with Google's security policies.

You can let the app developer ( know that this app should stop using unsupported OAuth flows.

Sign in with Google: Authorization Error - Error 400: Invalid Request


Starting in October 2022, Google says they will show Authorization Error - Error 400: Invalid Request message for any App using the deprecated function.

According to Google's Documentation: "OAuth out-of-band (OOB) is a legacy flow developed to support native clients which do not have a redirect URI like web apps to accept the credentials after a user approves an OAuth consent request. The OOB flow poses a remote phishing risk. PC Apps must migrate to an alternative method to protect against this vulnerability.".

CompanionLink and OAuth OOB

CompanionLink is ready with the new Google OAuth method. You will need CompanionLink Version 9 (build 9070) or CompanionLink Version 10 (build 10014 or higher). This is a drop in replacement. You might be required to sign into your Google Account via CompanionLink again after updating. If you are in sync with Google currently, there will be no change needed until the OAuth token needs to be refreshed.

How to get the latest version of CompanionLink:

  1. Click Here to download the latest version of CompanionLink.
  2. Once downloaded, click the downloaded setup file and click Install.
  3. Select Yes on the Windows UAC popup.
  4. Select OK to Finish the installation.

If you have an existing license to CompanionLink *Click Here to verify which version of CompanionLink you can use.

Switching to CompanionLink from a Competitor

How to Sync Outlook with Google

While CompanionLink has been ready for the OAuth OOB change since the announcement, our sync competitors might not be as quick to fix the issue. CompanionLink is offering a $10 discount for converting to our Google and Outlook sync solution. This discount applies to anyone who has used the following sync tools:

  • Sync2
  • gSyncit
  • OggSync
  • Go Contact Sync Mod
  • Outlook Google Calendar Sync

For a Free Trial of the latest version of CompanionLink for Google click the following link for our Downloads Page.

  • To claim your $10 discount:
  1. Use the following link to Buy CompanionLink for Google.
  2. Enter Product you are switching from in the "What Motivated You to Purchase" box.
  3. Enter "OOB22" in the Affinity Code Box.

CompanionLink for Google
Average User Rating:
Average rating: 4.86 out of 5 based on 628 reviews.
Free 14 day trial. Price $14.95 3-Mo Subs - $69.95 One-time License.