Hello, why i can’t update ios for my iphone 8plus? It says software update eror

Make sure you have enough storage on your phone, hold the off button for around 10 seconds until it turns off and then turn it on again, if that doesn’t work I would recommend speaking to someone on Apple support. Good luck!

There have been an unusually high number of people reporting software update and backup restoring problems over the past week. I certainly can’t know for sure, but I believe that the issue is in Apple’s end and until they work it out, you will have to wait or just keep trying.

Can you try to update with iTunes instead?