If you receive an internal server error or servlet container error (either unavailable or being upgraded), iManager is having problems with Tomcat:
Wait a few minutes and try again to access iManager. If you still receive the same errors, you need to verify the status of Tomcat and, if the error persists, the status of Apache.
Check the Tomcat logs for any errors.
The log file is located in the $tomcat_home$/logs directory on the UNIX*, Linux, and Windows platforms. On UNIX and Linux, the logs are named catalina.out or localhost_log.date.txt; on Windows, the log files are named stderr and stdout.
On NetWare®, any errors are sent to the logger screen.
Check the Apache log files for errors.
The files are located in the $apache_home$/logs directory.