Setup: I’m trialing Mattermost and have a self-hosted Mattermost server, setup in Docker on an Azure VM with a custom URL and NGINX to provide SSL. Almost everything is working fine, I can access Mattermost from my custom URL with HTTPS - However, I also have SSO configured through SAML with Microsoft Entra - The SSO login works if I log directly into my Mattermost server, but if I log in through the Mattermost custom App in my O365 App portal, I get an error: “The service provider Office365 did not provide an authorization code in the redirect URL.”
I followed this guide to set up SAML through O365 and have confirmed the URI settings: Entra ID Single Sign-On - Mattermost documentation
I’m thinking it may be something with my NGINX proxy settings, but I haven’t been able to find a lot of info on this specific issue or how to troubleshoot why MS isn’t sending the Auth code or assertions in the URI request.
Thanks!