Why [cellular update failed] appears on my phone?

Hi there Ye8, it sounds like you're seeing an alert about a failed cellular update. We can help.

We see that you came to Apple Support Communities from If you see an Update Failed or Apple Pay Not Available alert after iOS update or restart. If you followed the steps under "What to do next” and you still aren’t able to connect with your carrier’s service, it’s time to contact Apple Support: Get Support

Take care!