Originally Posted by zeyadrani
i flashed stock firmware 4.1.2
yeah I know but which one (the build number) something like XXELLA or XXEMG4...? you can see it in settings menu
in fact if you have flashed a firmware older than XXEMG4 then also its baseband is flashed, and these old basebands are not compatible with efs v2 which has been flashed through your sammy 4.3 update.
This could PROBABLY have caused your imei problem and you would only have to flash a baseband newer than XXEMG4 to PROBABLY solve it. or your efs is corrupt than you should follow the steps in the stickies