
Ensure the SEC_DIAG_TOOL service is activated. You can do this at the transaction code SICF.

Next, open your web browser and paste the following URL. Replace the hostname/port/client with your SAP information.
https://[HOSTNAME]:[PORT]/sap/bc/webdynpro/sap/sec_diag_tool?sap-client=[CLIENT]
Enter a name for the trace file and leave the default value as debug. Click on Start. You will see the trace is running now.

Now open a different web browser (if you are using Chrome for the above step trace, you can use Edge/Firefox for this step). You can start reproducing the error.
Once reproduce steps are completed. You can go back to the trace browser and click on Stop. You can download and analyze the issues from the collected trace file.

Reference
- 2960670 – How to collect SAML trace with the Security Diagnostic Tool for ABAP system
- 2501320 – How to get necessary traces for analyzing SAML2 issue in Netweaver ABAP system
- 2193465 – How to trace ICF service using HttpWatch
- 1990706 – How to capture an HTTP trace using Google Chrome or MS Edge (Chromium)

