After upgrade to CICS Transaction Server (CTS) 5.6 , Ideal online installation verification transaction for the web , IDWV , runs fine but the CICS log shows
DFHWB0002 A severe error (code X'0505') has occurred in module DFHWBSR
z/OS
CTS 5.6 and higher
Missing CICS URIMAP definition for FAVICON
Add CICS URIMAP(FAVICON) in Ideal group IDLWEB for your HOST as found in the sample provided in : How URIMAP is Used - Exceptions