[Galaxy S III General] Andro Boy:
my long and really annoying experience with "efs" folder

My problem started when i wanted for the first time to flash a custom ROM ,

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** I made an Nandroid Backup first by using (Online Nandroid Backup from store) as recommended in some threads, i did it by using custome recovery but didn't change anything but the name, but discovered later that it didn't backup my efs partition :( so when i tried to restore it it did restore all the old ROM but not efs .

**note: the new version of "online Nandroid backup" when i tried to make an normal backup "later" without changing anything it do backup the efs drive now by default .

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First i downloaded a couple of ROMs that i liked and after flashing the first two with working great without any problems (by using aroma installer and had chosen efs backup option in it, i didn't even know then what "efs" meant but i backed it up anyway :D )

i was trying all of them to decide which is better , so after the 3rd ROM i had the "not registered on network" problem and 0049 IEMI of course i searched a lot to solve the problem and tried all the solutions but they all didn't work so i had to send it to repair because i didn't have made a efs backup ,, it was already out of guarantee so anyway i took the device for Samsung and they told me that they will have to open the device and put a new IEMI for it by replacing some chip inside it of course it will coast a lot and i didn't think it was the only way either so i took it to a regular workshop and the guy their tried to change it by using a kit but it failed every time he tried to re-write the IEMI it succeed but after restarting the mobile nothing is done still 0049 so he gave it to me (after 1 or 2 weeks of trying) , so i tried to "google about it" again and i saw a thread here on XDA someone was having the same problem, so i was reading the replies and someone said that he made a backup of the efs folder and format it (he was really desperate as he said :)" ) and unzipped the backed up efs.tar by using winrar and put the files manually by using fx explorer to gain root access to the system files and placed it in the efs drive and restarted the phone and it worked !!

so i did the same (i was desperate too) but when i unzipped the efs.tar file i found a efs folder inside the already unzipped one so i copied it to the efs folder and restart it and it really worked ! , i don't know but i guess that the modem changed the efs drive and put the old one into a new folder inside the drive so any other ROM couldn't read it .

I DISCOVERD LATER WHEN I RETURNED TO THE ROM THREADS I USED LATER THAT THE FIRST TWO ONES THAT I USED WAS BASED ON THE LATEST MODEM FROM SAMSUNG "XXEMG4" X_X , BUT THE 3RD ONE WASN'T SO IT COULDN'T READ THE EFS FILES .

Conclusion for those who didn't done anything yet :

Before flashing any ROM especially custom ones BACKUP YOUR EFS FILES by any application u want (i prefer online nandroid backup) make a custom backup and choose only efs drive and save it for later use .

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Well I hope that anyone did understand anything from what i said :)" and that i helped by anyway ,

Thanks ..

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EDIT : Guys when u install any ROM with XXEMG4 modem u would notice nothing, and as long as u flash any other ROM with the same modem it's OK but the problem is if u flashed any other modem OVER it now the problem will occur (NO IEMI ,Network etc..) , BUT to resolve it it's easy if u have backup of your old efs files just flash it or do it manually by placing the files into the efs folder by using any explorer with root access .

PS: i have just downloaded "Pardus HD RoM Sensation White" and it has the EMG4 modem, after flashing their was no problem except that the IEMI changed to something like that (19H5q325t3H413653gb) long some unknown numbers and because i have dual boot so with the EMG4 modem the other CM10.2 ROM didn't have network but anyway just by flashing the old efs everything was OK and it worked for the booth just fine .