We deeply regret that on Thursday, July 30, some of our customers were unable to use Threema in the usual way. Two unfortunate circumstances beyond our control led to these failures. In the interest of transparency, we would like to briefly explain the causes. We apologize to all Threema users for the inconvenience.
Issues with Threema 2.4.0 under iOS 7 and older
Threema version 2.4.0 was tested by us under iOS 7, 6 and 5, and worked fine using the available distribution methods for beta testing under these older iOS versions (i.e. installation via Xcode or AdHoc). However, it seems that the repacking/resigning that the App Store performs for distribution broke the binary and made it impossible to launch on iOS 7. Unfortunately this could not be verified before release, as Apple's official beta testing solution in the App Store, TestFlight, only works on iOS 8. We have submitted another update (2.4.1) on Thursday to fix the problem, which is currently waiting for review by Apple.
Network outage on July 30th
On July 30th, the Threema servers were unreachable for most users between approximately 10:10 and 12:30 CEST, except for a small percentage of users whose ISP had a direct route (peering) with our colocation provider nine.ch. The reason was a fiber cut that brought three data centers offline and destroyed the otherwise redundant uplinks. For details, please see https://status.nine.ch/en/messages/471. Threema’s infrastructure was up and running all the time, but unfortunately partly unreachable due to this network outage.