Error "Could not reserve enough space for object heap" When Starting JDeveloper or SQL Developer

CAUSE:

Wrong memory parameters in jdev.conf (JDeveloper) or sqldeveloper.conf (SQL Developer)


SOLUTION:

Go to

configuration file jdev.conf or sqldeveloper.conf:

Here you will find only one option

AddVMOption -Xmx1024M


Just replace it with

AddVMOption -Xmx1024M
AddVMOption -XX:MaxPermSize=256M