We are receiving 500 error whenever we make a request with the target containing "?" in the URL.
Webagent version: SiteMinder agents running on 12.51 version
We were receiving 500 error because the agent was converting ? to %3f with the encoding of ASCII representations, so our webagent will change that to %3f and as a result show the 500 error message.
As a workaround we can use the "relative target in the authentication scheme" when the same server can be used for an authentication scheme where the application resides and we cannot use it if we have dedicated and centralized login server.
We can upgrade to 12.51 CR01 to resolve the issue when we have agent on the another server or we are using any centralized server for an authentication schemes.