Intermittent Login issue R12.1 – 500 Internal Server Error

Problem Description :

Users are unable to get application login page.

Users are frequently getting below error while accessing the EBS application R12.1.3 URL.

Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, ohs_admin@acs.net and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.

Cause :

This issue occurred due to low oacore heap size.

Solution :

Increase the oacore heap size and restart application services.

Change the parameters in $ORA_CONFIG_HOME/10.1.3/opmn/conf/opmn.xml

of both form nodes as shown below:

From :

-Xmx512M -Xms128M -XX:MaxPermSize=160M

To :

-Xmx1024M -Xms128M -XX:MaxPermSize=160M

Reference :

JVM: Guidelines to setup the Java Virtual Machine in Apps E-Business Suite 11i and R12 (Doc ID 362851.1)