KB180107158: WebCenter - NullPointerException instead of login page

Summary

When trying to reach the Login page, a null pointer exception is thrown. The URL will look similar to the following: 

http://webcenterurl/WebCenter_Inst/showerror.jsp?message=java.lang.NullPointerException&h=218B0E433E7E5475F8F478ED4A91192FB0DF5BAB7B9D34775E5BF15B3FA50067

and the page itself shows the following error:

"Error processing your request. Please try your action again.".

Symptoms

In the catalina log file, you will see the following error:

2016-06-06 16:05:28,558 INFO  [com.esko.webcenter.jsp.WebAppTimer] {59} -> cancelImpl: Timer com.esko.webcenter.jsp.WebAppTimer;instance:/WebCenter_Inst stopped
2016-06-06 16:05:28,574 ERROR [org.apache.catalina.loader.WebappClassLoader] The web application [/WebCenter_Inst] appears to have started a thread named [class com.esko.webcenter.log.Log4JWrapper-asyncExec] but has failed to stop it. This is very likely to create a memory leak.

Solution

Tomcat will be running with a different user who is not in the local administrator group and therefore does not have enough rights to stop threads.

There are two options to solve this issue:

1. Add the user who is running Tomcat to the local administrator group on the server by going to Local users and groups and then restart Tomcat.
2. Run Tomcat with the default Local System user. To configure this:
   
   1. Go to Services, stop the WebCenter Tomcat Web Server service.
   2. Right click on this service to open the contextual menu and click Properties.
   3. In the Log On tab, select the Local System account radio button and starting the service again.