Google's OAuth 2.0 policy - Error 400 redirect_uri_mismatch

Question

I tried to run the github solution (https://github.com/SyncfusionExamples/google-calendar-synchronization-with-blazor-scheduler) associated with How to Synchronize Google Calendar with Syncfusion Blazor Scheduler Demo.

I changed it to a .Net 6.0 solution, updated the NuGet packages and added the redirect_uri = https://localhost:5001/ when configuring the OAuth 2.0 Client IDs credentials and downloaded the credentials.json file. I keep getting the following error and on re-running, the port number in the redirect_uri changes ......

Error 400: redirect_uri_mismatch

You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy.

If you're the app developer, register the redirect URI in the Google Cloud Console.

Request details: redirect_uri=http://127.0.0.1:53883/authorize/

Any ideas/suggestions on how to get this to run.

Ashokkumar Karuppasamy · Answer

Hi Ola,

Based on the provided details, we suspect that this issue is related to Google
authentication. Please refer to the public forums below where similar issues
have been discussed:

https://www.googlecloudcommunity.com/gc/Developer-Tools/Getting-error-redirect-uri-mismatch-when-using-oAuth/m-p/608233https://groups.google.com/g/google-cloud-dev/c/stahW8o5KJk?pli=1https://stackoverflow.com/questions/28321570/google-oauth-2-0-error-redirect-uri-mismatchhttps://stackoverflow.com/questions/11485271/google-oauth-2-authorization-error-redirect-uri-mismatchhttps://stackoverflow.com/questions/73799334/i-get-this-error-error-400-redirect-uri-mismatch-even-after-i-registered-thehttps://stackoverflow.com/questions/75195100/google-oauth2-redirect-uri-mismatch-400

Regards,
Ashok