Invalid Grant for SAML Assertion Flow

Questions SAML
1

Hi,

I’ve been banging my head against the wall for days on this particular problem!

I have followed this guide to the letter. I am able to get a SAML response and what appears to be a valid SAML assertion. I base64url encode the assertion and add in the body of my post request like so (with form URL encoding checked):

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I also add a content-type: application/x-www-form-urlencoded to my headers. The post request is being made to the default authorization server at https://.okta.com/oauth2/default/v1/token. I’m also using basic auth with client ID and secret.

I keep getting an “invalid_grant” error with the message “‘assertion’ is not a valid SAML 2.0 Assertion”. I’ve ensured that the assertion is not expired or previously used, checked the audience/recipient headers against my Okta setup, and ensured that the assertion is signed. Everything seems to be in order.

Anyone have an idea what would be causing this issue?

Thanks in advance!

2

Also, in case it helps: each time I make a request to the /token endpoint, I get the following in my system log:

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3

Hello,

I send you a direct message to see if you can supply one of the SAML Assertions that is failing.