If you’re using a modern jailbreak that uses Cydia Substrate as its primary means of tweak injection, be it checkra1n or unc0ver, then today might be a good time to fire up your preferred package manager and refresh your sources.

Substrate Safe Mode appears to have been updated to version 0.9.6003 with a critical bug fix. The checkra1n team shared the announcement in a Tweet delivered early Friday morning:

From what we can gather, the critical bug that was patched in this update involves a failure to boot while in jailbroken mode. Given the rather dire circumstances, you can see why it might not be a good idea to put off updating to the latest version of Substrate Safe Mode.

Like all previous versions of Substrate Safe Mode before it, the latest version is being hosted on the default checkra1n/Sam Bingner repositories on the checkra1n and unc0ver jailbreaks. The only exclusion would be A12(X)-A13 devices jailbroken with unc0ver, as these would use Substitute instead.

Have you updated to the latest version of Substrate Safe Mode yet? Let us know in the comments below.