AT&T and Samsung has been released official OTA update for the Galaxy S4 with baseband version I337UCUAMF3, maybe this is good news for non-rooted users, but otherwise this is an update that should be avoided by the user who has root access. As reported by several users at xda-developers, this update allegedly contain new security patches, so when you download and then install the MF3 OTA update then you will lose the root privileges.
The latest update I337UCUAMF3 also prevent you to perform root again through the help of Motochopper exploit from djrbliss, which works with previous firmare version. Any attempts to maintain root after install the update also failed, if you set up voodoo Rootkeeper before receiving an OTA and hope to restore it later, then you will fail. Additionally, the MF3 OTA update also prevents you to downgrade to the previous firmware version, so for now you can’t return to I337UCUAMDL and now you stuck with the latest build number (JDQ39.I337UCUAMF3).
Update: New exploit for MF3 firmware has been found, go to this post for the guide.
We all know, this OTA update provides several enhancements and bug fixes, including: Enable LTE Bands 2 and 5 NFC, Broadcom chipset firmware updates, and fixing a lot of things (rebooting issue, Wi-Fi compliance, Drive Mode SMS, Email/Calendar), however there’s no improvement to support App2SD, which is a long awaited feature. If you want to avoid this from happening again, you can block an OTA update on AT&T Galaxy S4.