When i run oracle reports 11g in my windows 7 it gives me this error
rep:50125:rwbuilder.conf:java.lang.NullPointerException
My run shortcut path is
G:\Oracle\Middleware\as_1\bin\rwbuilder.exe
I solved it in my case go to oracle directory and search for rwbuilder.bat it will show three results , one is in the path i.e in my case
D:\Oracle\Middleware\asinst_1\config\reports\bin\rwbuilder.bat try to run and it will work
This solution is for the most but not the only and may not solve your problem