The error "invalid_scope" typically occurs when the requested scope is not valid or not configured correctly in the authentication settings.
In your case, if you're encountering the error when adding the "Online.Meeting" scope in the URL, it's possible that the scope is not supported or recognized by the authentication endpoint. To resolve this issue, you can try the following steps:
Double-check the scope name: Ensure that you're using the correct scope name. It should be "Online.Meetings" instead of "Online.Meeting". Verify the correct scope name in the Microsoft Graph documentation or the documentation specific to the API you're trying to access.
Verify application permissions: Make sure that you have the necessary application permissions configured for the "Online.Meetings" scope in the API permissions of your app registration. This step ensures that your app has the required permissions to access the Online Meeting API.
Check user consent: If you're using delegated permissions, ensure that the user has consented to the required permissions. In some cases, the "invalid_scope" error can occur if the user has not granted the necessary permissions to the app.
Clear cache and try again: If the above steps don't resolve the issue, you can try clearing the cache of your application and attempting the authentication flow again. Sometimes, cached tokens or settings can cause issues with scope validation.
If the problem persists after following these steps, it might be helpful to provide more details about your authentication code, including the specific library or framework you're using, and any additional error messages or logs you're receiving.