The Control-M/Enterprise Manager Web Client does not start up and a blank/white page appears

For example:
Open the Control-M Welcome page (https://hostname:8443/Welcome), and when clicking on Control-M Web the page is blank/white with no messages.  This can also happen in other situations when opening the web client



After clicking on Control-M Web, the next page appears blank, with no messages




In the file catalina0.out there are some errors and warning messages:

2023-07-17 09:19:49 WARNING [Catalina-utility-6] org.apache.catalina.loader.WebappClassLoaderBase.clearReferencesThreads The web application [automation-api] appears to have started a thread named [http://localhost:32080/] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 java.base@17.0.7/java.io.FileInputStream.readBytes(Native Method)

2023-07-17 09:19:51 SEVERE [Catalina-utility-6] com.sun.xml.ws.transport.http.servlet.WSServletContextListener.contextDestroyed java.io.IOException: java.lang.reflect.InvocationTargetException
    java.lang.IllegalStateException: java.io.IOException: java.lang.reflect.InvocationTargetException

2023-07-17 14:19:00 INFO [http-nio-18080-exec-20] org.apache.coyote.http11.Http11Processor.service Error parsing HTTP request header
 Note: further occurrences of HTTP request parsing errors will be logged at DEBUG level.

2023-07-17 14:49:16 WARNING [pool-15-thread-1] org.apache.tomcat.jdbc.pool.PooledConnection.clearWarnings Unable to clear Warnings, connection will be closed.
    org.postgresql.util.PSQLException: This connection has been closed. 

Windows:

1. Stop the Control-M/Enterprise Manager Configuration Agent Windows service.

2. Open a command prompt and run the following commands:
stop_web_server
remove_webapps

3. Start the Configuration Agent service and wait a few moments to let the processes start

4. Check the web page

Unix/Linux:

Login as the "emuser" and run the following commands:

stop_config_agent
stop_web_server
remove_webapps
start_config_agent

Check the web page