Invalid Login Mode.
CAUSE: One possible cause for this issue is a spelling or syntax mistake in sys_defaults.xml configuration file under [Web_Deployment]/WEB-INF/xml. In this case, the parameter "enabledloginmode" had a syntax mistake, making all selected login modes invalid.
ACTION:Compare the deployed sys_defaults.xml configuration file with a OOTB version to identify possible syntax or spelling mistakes. Alternatively, re-deploy a fresh copy of the out of the box WAR file when using Strategy Web JSP or perform a repair installation when using Strategy Web ASPx.