X-CSRF Issue while calling from JAVA appplication

[xianmi]

Unable to post data (Purchase Requisition) into S/4 HANA system because of security token issue due to x-CSRF token mechanism enabled in oDATA service and we need to have this interface working with this security feature in place.

Steps to post data in S/4:-

1. SAP standard OData service " API_PURCHASEREQ_PROCESS_SRV" is being used for PR creation
2. We are using IntelliJ IDE for creating a JAVA REST Service Client to call S/4 - payload is attached
3. FETCH is used to get CSRF token as a pre-post
4. POST is used to post data
5. We debugged on S/4 side and method "validate_csrf_token" of class "/IWCOR/IF_REST_CSRF_HANDLER" is returning flag "lv_successful" as blank which is causing the issue
6. On the JAVA side, we receive "HTTP: 403 Forbidden Error"

We need your help and support in figuring out why the class method is not returning a success flag even though we are able to fetch the x-csrf token successfully from S/4 and use this token during POST.

[gregorw]

Do you provide the user authentication information from the client?

[Andre_Fischer]

In addition to what Gregor mentioned try to perform a payload trace using transaction /iwfnd/traces.