I recently got an iPhone XS Max and decided to restore from the previous backup of my iPhone 8 plus. However, I have met a massive issue whereby every time I click on restore to backup I got the error message “Installation Failed: Can’t Install the Software”. Of course, this was annoying and very frustrating and I just could afford to lose the things I have on my iPhone. I made numerous attempts, about 20 times in fact, but kept getting the same error message.
I then realise that the connection to my iPhone and MacBook would pop on and off leading me to think that something is going on with the connection between the two. I also released that the time and date of my Mac and iPhone were not the same. This is the first thing I did. On my, iPhone I went into settings>general>date & time and change it to match with my Mac. I then tried again but no success. I was using the old lightning for my iPhone 8 Plus to try and update the software. I simply switched to the new lightning cable and everything was resolved.
So the issue would appear to be with the lightning cable. I can only think that this is Apple’s doing and the software for the cable is what they have messed with. if you ever come upon this problem, which you will, then you now know the fix.