Customer is seeing a large number of 500 errors in the web agent trace log. These are all requests for the creds.kcc file (Kerberos authentication). The agent logs indicate that the OPTIONS method is not supported:
[03/01/2023][18:30:47][22a58804-c8f42d32-57bbcbfa-5c79da8a-5a2cd811-52][CSmHttpPlugin::ProcessAdvancedAuthResource][HTTP method options not supported in Advanced Auth]
Release : ALL
The HTTP OPTIONS method is not supported in against any file associated with advanced authentication methods which include forms, X509, IWA, and Kerberos.
These errors are benign since browsers will ignore the error with no effect on the users (browser subsequently sends the expected GET request after receiving the 500 on the OPTIONS request).
The web agent does support OPTIONS requests for all other resources. Since browsers will not present any cookies with an OPTIONS request, it is common for customers to set AutoAuthorizeOptions=Yes in the Agent Configuration Object (ACO).
AutoAuthorizeOptions ACO Parameter: