iPhone Why can't I downgrade from 13.4 to 13.3.1?

[Magnus Wehus]

The battery is draining so much quicker on 13.4 and I can feel the phone getting hot even with normal web browsing which it did not do before the upgrade to 13.4 on my iPhone 11 Pro.

I have downloaded the 13.3.1 ipsw file and try to restore it (restore mode and DFU mode), but its not working. Getting "Unknown error (1)" at about 80% of the installation, no matter what I do.

I have tried to switch cables, tried to unplug everything else that was connected to the computer. Even tried to do the same routine on a different machine which is not running Catalina.

It works however to restore and update to 13.4 again.

What could be the problem?

 

[Mervyn Mcintyre]

i have the same problem, dfu and recovery with 11 pro max, reset all settings and th only back up i had was 13.4 so didnt restore from back up, and still it restored back to 13.4, i downloaded 13.3.1 ipsw and restored with option pressed and still the same

 

[Magnus Wehus]

i have the same problem, dfu and recovery with 11 pro max, reset all settings and th only back up i had was 13.4 so didnt restore from back up, and still it restored back to 13.4, i downloaded 13.3.1 ipsw and restored with option pressed and still the same

super weird. BUT I figured out a fix for the battery drain. I installed 13.4 from the ipsw file instead of over the air (dont know if this had anything to do with it), and deactivated Siri completely. Im pretty sure that Siri is the battery thief here. Will just let her be deactivated until the next iOS update I guess.