POST to login using SAML2

[Barbara_Post]

Hello, I'm trying to get an access token with a SAML POST request to PureCloud login server, providing a SAML Assertion I just generated. Please can you help me finding what's wrong?
Thank you very much.
Here are screenshots using Postman:

[tim.smith]

Please open a case with Genesys Cloud Care to investigate further. We do not have access to your private information to troubleshoot this via the forum.

[Jerome.Saint-Marc]

Hello,

I just noticed that you are using "grant-type" as key in your body. That's not the proper key/name - it must be "grant_type" as described here.
That's probably the reason of your HTTP error.

Regards,

[Barbara_Post]

Better, but I left this task for now. Thanks for seeing my typo Jerome.

{

    "error": "invalid_client",

    "description": "client not found",

    "error_description": "client not found"

}

[Jerome.Saint-Marc]

That invalid client error should be because Genesys Cloud cannot find a SAML OAuth Client defined in your region (mypurecloud.de) with the provided clientId.
Seeing the beginning of your Authorization header (screenshot), I think your Authorization header is not encoded properly - or the base64 value includes a character it shouldn't include. Decoding PWRj, it gives: =dc and the Genesys Cloud OAuth clientId value can't start with an =
The value is base64 encoding of clientId:clientSecret

Regards,