There are many issues and problems that can occur on your Samsung Galaxy S6 and Galaxy S6 Edge while messing with the system partition by installing custom ROMs, mods and kernels. You can go into a bootloop, brick your phone or lose your EFS folder.
The EFS folder is the most important part of the system because it has every information about IMEI and baseband version. Even though something like this happens rarely, when you flash a custom ROM, there is a slight chance that the EFS folder might get corrupted.
When this happens, IMEI goes null and baseband version under Settings > About Phone shows unknown. If this was everything a corrupted EFS would do, everyone would be happy. However, a null IMEI and unknown baseband version blocks you from making phone calls, sending SMS messages or using mobile data. The EFS folder allows the phone to communicate with the SIM card. When it gets corrupted, it is no longer able to make the communication. Here are a few possible solutions to fix the problem.
How To Fix Samsung Galaxy S6 & S6 Edge Null IMEI
Flash Stock Firmware
Most of the times, the corrupted IMEI folder will fix itself when a new stock firmware is installed. Since the problem occurs when a new custom ROM gets installed, this means that the ROM is buggy and doesn’t work properly. To go back to stock, you have to download a stock firmware for your Galaxy S6 or Galaxy S6 Edge and flash it through Odin. Here’s a detailed guide how to flash stock firmwares on Samsung Galaxy S6.
Restore EFS Backup
Most of the ROMs automatically make a full backup of the IMEI folder before flashing. If you lucky enough to have a backup on your phone, you can restore it by using “Backup & Restore Partitions“. Click the link to learn how to use the app and restore the EFS folder to fix null IMEI problem.
These are some of the solutions that have worked for many users. If you have any other suggestions, please let us know below.