JDeveloper Startup Error: Unable to create an instance of Java Virtual Machine

Faced this error the other day while starting Oracle JDev 11g (known to happen across JDEv versions) and may appear suddenly even after you have already used the same it several times.

Solution:

In order to fix this go to <Install_Directoy>\Middleware\JDeveloper\jdev\bin folder

and edit file "jdev.conf" 

Locate the line "AddVMOption -XX:MaxPermSize=256M" in the file and add another line just below this line:

AddVMOption -Xmx256M

[ Additionally, you may also want to increase the IDE JVM memory allocation by modifying the file "ide.conf" located at <Install_Directoy>\Middleware\jdeveloper\ide\bin folder.

Locate and edit the VMOption parameters to increase the Xmx to 1024M and Xms to 256 or 512M

#
AddVMOption  -Xmx1024M
AddVMOption  -Xms256M ]