Unable to login to OneClick on Spectrum 10.2.3
The port must be available in order for Tomcat to bind and allow incoming connections.
In a recent issue CA found that the Windows OS was taking up/not letting go of the Tomcat HTTP Port.
Even a netstat was showing the port as free, but Tomcat would still get errors.
Upon configuring a different port - Tomcat started successfully.
Generally a reboot will fix these types of issues with the OS and CA suggests rebooting before calling CA Support.