ios 13
My iphone x will not update to ios 13. I keep trying and it will not. it just restarts.
iPhone X
How are you trying to update it? Are you updating from iTunes or directly from iPhone?
If you are trying to update from iPhone directly, you may not have enough space. In this case, you would have to connect your iPhone to iTunes and update there.
If you are trying to update from iTunes, here is a support article. https://support.apple.com/en-us/HT201210