Upgrades iOS through an intermediate version

Last Saturday a friend of mine asked me to help solving the problem that she couldn’t see any images in the WeChat app on her iPhone 4S.

I found that this iPhone 4S was running with iOS 5.0 which is behind the times, and I thought that this is the reason. Then I clicked the Settings app and found that the iOS prompted that it could upgrade to iOS 6.1.3 instead to iOS 7 — this surprised me. And I let it to upgrade. A short while after the successful upgrade to iOS 6.1.3, iPhone 4S prompted that it could upgrade to iOS 7.0.6 — I certainly ignored this prompt and advise my friend not to upgrade to iOS 7.

In summary, Apple introduces an intermediate version (6.1.3) to let iPhone 4S which is running iOS 5 to upgrade to iOS 7 – two upgrades. It’s a little an annoying for users, but this method

  1. not only reduce the complexity – reduce from maintaining 3 upgrade scenarios (5->6, 5->7, 6->7) to 2 (5->6, 6->7);
  2. but also can provide more security of the data in the device during the upgrade (more scenarios means more possibility to make mistake).

By this experience of upgrading iOS, I recalled that a CT platform I was working for 5 years ago (2009) used this intermediate-version method to upgrade the systems which are residing in operators’ device house and are serving for millions of mobile phone users — we have only about 4 or 5 hours (0:00/1:00 AM to 5:AM) to upgrade the system, and if something go wrong, rollback must be applied.

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