iPhone 16 Pro stuck in 'unavailable' mode despite no passcode attempts

Suzi_Q wrote:

My i phone 16 Pro, running iOS version 18.6, became "unavailable" without any attempts to enter passcode last night. I wake it up and the unavailable message is there. I try turning it off and back on, but it just starts the 5minute wait time over again. I went to bed and decided to just wait and go to the Apple Store for help the next morning. This morning I pick up my phone and get the 5 minute timeout screen again so I waited the 5 minutes, pickup my phone and suddenly it’s working again. No one else has access to it. What is causing this and how do I correct it?

[Re-Titled by Moderator]

Original Title: Unavailable screen

Reset or a Force Restart,

Force restart iPhone - Apple Support

Restore from backup, restore as new device.

Restore your iPhone, iPad, or iPod to factory settings using a computer - Apple Support

Put your iPhone in diagnostics mode - identify potential hardware and software issues

How to put your iPhone in diagnostics mode - Apple Support

The current stable release of iOS including bug fixes, security updates is iOS 18.6.2

Update your iPhone or iPad - Apple Support