MuscleNerd has confirmed that UltraSn0w update is coming for iOS 4.3.1 in a few days. The unlock tool has had several bugs and is currently incompatible with several older basebands.

To clarify: the upcoming UltraSn0w update will not unlock any new basebands. The update is meant for current unlockers that wish to update to the latest 4.3.1 jailbreak and keep their unlock.

As we previously mentioned, the new version of UltraSn0w will fix all compatibility issues with the latest version of iOS.

As MuscleNerd mentions, the signal bar bugs, etc. have been fixed and are currently being tested to ensure stability. The UltraSn0w update will soon be available in Cydia for current unlockers.

If you rely on an unlock for your iPhone, hold off on updating your jailbreak to 4.3.1 until UltraSn0w is made compatible with your baseband. If you have a new iPhone 4 (Verizon iPhone included) and have never unlocked your device, you still won’t be able to do so with this UltraSn0w update.

JailbreakMovies explains how the update will work,

“Just a note that for those of you experiencing the issue even with a baseband version that doesn’t qualify for an unlock, you can still use this version of UltraSnow, as it will skip the unlock, and just fix the signal bar issue.”

Unlockers must use PwnageTool to jailbreak iOS 4.3.1 and preserve their baseband for the updated unlock. Check out our tutorial on jailbreaking with PwnageTool. You can also use Sn0wBreeze on Windows to preserve your baseband.

We’ll keep you posted on when UltraSn0w’s update goes live in Cydia. Let us know if you have any issues with your unlock below!