Why does Apple X send you a zero-host c sim card when it is turned on?

This is because you clicked on the sim card application or the sim card application is being updated. Just refresh the SIM card application.

Option 1: Turn off the iPhone, take out the SIM card, reinstall it, and then turn it on. Option 2: manually refresh the SIM card.

Enter the iPhone settings, click "Cellular Mobile Network", and find and open "SIM Card Application" in the interface. Click any item in the "SIM card application" that pops up. After clicking, the following interface will pop up. Click an option at will again.