Software Update Failed Error for iOS 15.7 on iPhone 8

I had the same problem -- tried to install iOS 15.7 on iPhone 8 and got the "software update failed" error.

Here's what worked: I freed up enough storage space until I had about 9 GB free. That's it.

I originally tried when I had about 4-5 GB free. It didn't install, and I got the exact same error as above.

I tried again when I had about 7 GB free. It still didn't install; same error.

Once I freed up enough storage space (by deleting apps and things) until I had about 9 GB free, then the update installed, no problem.

To the people claiming you need approx 10+ GBs of free storage on your phone for the new iOS to successfully install...what about those of us who literally can't free up that much memory? My phone's only 25GB, I already transferred nearly all my photos and managed to successfully download the new iOS, which took up 5GB. I have 6.3GB of extra memory right now and literally nowhere to get more memory space from. I've been trying to install it for three hours now to no avail. I need to update my iPhone SE due to WhatsApp policies as they will stop supporting my current version of iOS. Am I seriously supposed to buy a new iPhone solely due to the fact that the update requires an ungodly amount of free memory storage, which isn't even listed anywhere?

Same thing is happening to me, I have an XR aswell. It’s so annoying.

Same issue with my iPhone 11. Reset network settings, powered off/on, force restarted but still gets the error message.

What if my PC don't let me connect my iPhone and when I try to do it, ask me if I wanna reset and start as a new iPhone?

still doesn't work too tho...

Yea same thing with me should I just install the 16 update

I have the same issue on iPhone 11.

And when I try to download version 16, I cannon for not the space issue, but I have free 4 GB on my phone.

I have the same issue with my iPhone 12, i also cant install the ios16 update bc phone keeps telling me that 15.7 is required

i have the exact problem

Same problem with an iPhone 8 Plus. Even force touch/long pressing the "Download and Install" button to just download or download and install tonight fail to work.

Same here with XR. Been trying for 2 days. Very frustrating. Looks to me like they rushed this update too fast.

I have exactly the same issue on my iPhoneXs, despite freeing 5 GB storage on my phone and resetting the network settings. Very annoying :(