'The Trailblazer Connected app is blocked in your Salesforce org' Error When You Try to Access Your Trailblazer Account

To resolve these access issues for your Trailblazer account, contact your system administrator who will need to follow the following steps:
 

1. Navigate to Setup and enter "Connected Apps" into the Quick Find search box.
2. Click Connected Apps OAuth Usage.
3. Look for the Trailblazer connected app.
   • If the Action button for the Trailblazer app says "Unblock", then this connected app has been blocked. 
4. To allow end users to access Trailblazer, click Unblock. 

Additional Troubleshooting:

In rare cases, the Trailblazer connected app may not show as blocked, even though a user is receiving the OAUTH_APP_BLOCKED error message. One solution to this scenario is to follow these steps:
 

1. If the Trailblazer connected app has been installed in your organization, uninstall it to revoke all of its existing tokens.
2. Locate the Trailblazer connected app as described above.
3. If the app does not show as blocked, click Block (you may need to wait up to a 15 minutes for the app to show as blocked).
4. Repeat the unblocking steps as described above.