Office 365 SAML token rejection
I have configured the Office 365 SAML iApp for authentication, and to all intents and purposes it looks as though APM is successfully authenticating a user and issuing a token. However when the token is submitted to Office 365 I receive the response:
Sorry but we're having trouble signing you in. We've received a bad response.
AADSTS50000 there was an error issuing a token.
I'm using a URI as an identified as opposed to a URN. I've investigated as much as I can (but by no means and expert) confirming certificate thumbprints are uploaded to O365, time is in sync. I have dug into the http requests with Fiddler. I can see the SAML request and response. I see it submitted in the header to O365. Verified users are synchronised to Azure AD. Furthermore I've checked for additional proceeding slashes in the configuration between APM & O365.
Really struggling to understand the problem. Any suggestions/ help would be greatly appreciated.