BEA-101020 only indicates that the servlet failed due to an exception. The real cause of the error needs to be validated by looking for the exact reason for the error message.

Error: [context] Servlet failed with Exception
Description : [context] Servlet failed with Exception
Cause : An unexpected error occurred.
Action : Check the exception for exact error message.

Example message below from one of our scenarios.. you can see in the error below that we got a bea-101020 servlet failure due to out of memory condition in PermGen space... We solved it by using increasing MaxPermSize=256m in our config. It can be done either by modifying the setDomainEnv file in present in the /bin folder or by modifying the value in the startManagedWeblogic script present in /bin folder to impact a specific managed server or startWeblogic script if you want the change to be specific to the Admin server.

<[ServletContext@25932797[app:Emlap_11 module:Emlap.war path:/Emlap spec-version:2.5]] Servlet failed with Exception
java.lang.OutOfMemoryError: PermGen space
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)