I keep on getting this when I try connect my microsoft account and authorise it. I have correctly added the client ID and Secret already but this is appearing. Could this be due to my companies method of authorising my email account.
Hi @Marcus_SPS Welcome!
invalid_client is Microsoft rejecting the client secret itself, which happens before your tenant’s consent policy is ever evaluated, so this isn’t your company’s sign-in method. In Entra the Secret ID sits right next to the Secret Value and the Value is only shown once, so the ID gets pasted by mistake very often, and an expired secret returns the same error.
In your app registration go to Certificates & secrets > Client secrets > New client secret, then copy the Secret in the Value column and paste that into the credential as the Client Secret. While you’re there, check the redirect URI is registered under the Web platform, not Single-page application.