

While the G Suite does offer us many outstanding products and services, we also didn’t feel that Gmail is up-to-par as a corporate solution the way Exchange/Outlook/OWA are – this alone was also a driving force for our end-users, as there was minimal transition for them to move from an on-premise solution to an off-premise solution. Therefore, it was difficult for us to look at alternatives to Microsoft for a solution – we did look at the Google Suite of products, but the transition for us seemed less cumbersome to stay with Microsoft from a staff and administrative perspective.

It's something that shouldn't happen and you don't check as a consumer. It was as unexpected as a car exploding when anyone but the registered owner sits in the driver's seat and turns the key in the ignition. That's why I didn't catch that in development. It looks like their OAuth2 server only works correctly when requesting permissions for the same pCloud account you used to create the OAuth2 application. While we pass back the client_id and client_secret they provided us in their web interface their OAuth2 server does not recognize the client_secret and throws the error you are experiencing.

Unfortunately this is a bug in pCloud's OAuth2 implementation, namely the oauth2_token callback.
