My watch keeps rebooting

Yep me too. Apple support are currently investigating and I’ve been told it’s looking likely that they will need to ‘service’ the watch. It was working fine before the update and I’ve only had the watch for 6 months.

What version of watch is it? It happened to me with the new 6 series already twice.

My watch is series 3

This will most likely occur if you are running beta software.