iPhone Factory restore without updating iOS?

[aperantos]

I am having a few problems and simply resetting my iPhone 6 will not help, so want to try a factory restore. The problems are with a G.P.S. bluetooth connection and a certificate trust. But when I go into DFU or recovery mode and select restore I get told I need the latest iOS, needing a new iTunes, on a much newer version of macOS.

Both the older iOS and macOS versions are for compatibility reasons, so I do not want to update either of them.

Many, many web pages say that selecting restore should allow restoring without updating, but iTunes will just not allow it. It always brings up the dialogue box saying I need to update everything else to use the latest iOS. And obviously option-clicking to select the original ipsw file gets rejected as Apple's server will not sign it.

So is restoring to factory condition without updating actually possible?

 

[BrianBaughn]

Not usually. Only if the original, older version of iOS is very recent and is still being "signed" by Apple.

Apple shouldn't even use the term "factory" when describing iOS device restoring…but they do!

 

[aperantos]

Thanks for letting me know, though in the end it turned out the problem was bad data in the iTunes backup and not something remaining on the iPhone after erasing it.

I was able to fix the G.P.S. problem by unencrypting the backup then restoring from that, so it did not save any bluetooth data. Luckily I do not use the Health app and passwords are stored in iCloud so I did not lose anything.

No idea what caused the certificate trust issues, but that still persisted. However just trying things out, I was able to bring up the option to re-trust it by editing the password in the settings.