Please contact the server administrator, email@example.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
Looks Like the Issue with the Apache.
Please check log in $LOG_HOME/ora/opmn - Location
Can you try the below steps, Bounce services and retest.
After sourcing the environment , Compile all JSP files .
Run the command :
ojspCompile.pl --compile --flush
Also refer : Please check R12: Troubleshooting 500 Internal Server Error in Oracle E-Business suite (Doc ID 813523.1) and see if it may give you any additional information.
-Chiranjeevi M A
Go your $LOG_HOME/ora/10.1.3 directories and check the logfiles and see for errors
Have you check dbc file & tns names.ora in application tier are correct.
What is the value set for jsp_compile in the context file ?
Try compiling the jsps manually. U will find notes on how to do that.
perl ojspCompile.pl --compile --flush -p 2
And then start services and check. Check the oacore log files to see if there are any errors captured.