This is a Tomcat class loader issue. For unknown reasons, Tomcat is picking the wrong class from an old jar that exists in the same environment. The jar file which we deleted wasp_api-8.4.0-K is an old jar that has the wrong namespace. The installer is supposed to delete that jar but it could not get deleted.
So Tomcat is picking a class from that jar instead of wasp-api.jar. We try to remove the unwanted jar in the next release.
Release : 20.3
Component : UIM - UMP_ADMINCONSOLE
1) Take the system to the state where adminconsole is not working
2) In IM(Infrastructure Manager) deactivate the wasp probe
3) Go to the product installation folder of the UIM server
4) Open \nimsoft\probes\service\wasp\webapps\adminconsoleapp\WEB-INF\lib
5) Find the jar file wasp_api-8.4.0-K
6) Take a backup of this file in another location (NOT in the same folder)
7) Delete the file from the original location
8) Delete work folder from the location \nimsot\probes\service\wasp\
9) Activate wasp probe in IM
10) Delete browser cache and run the adminconsole app in the browser