Thanks for reaching out in Apple Support Communities. I understand that you're seeing a message on your iPhone that your passcode has expired. I can see why you'd reach out about this; I'd like to help.
Use a passcode with your iPhone, iPad, or iPod touchIf an alert says to change your passcode or you can't adjust your passcode settings
Configuration profiles and email accounts based on Microsoft Exchange (common with business or education devices) sometimes have passcode policies that cause issues like this:
- You can't turn off your passcode.
- You can't change passcode settings because they're unavailable, gray, or dimmed.
- You see an alert about a Passcode Requirement. For example, you might see a message that says you must change your iPhone unlock passcode within 60 minutes.
Contact your IT administrator for help. If you don’t use a configuration profile or Microsoft Exchange account, or if your device is personally owned, make sure you update your device to the latest version of iOS.
If you're not sure if you have a configuration profile installed, tap Settings > General; do you see Device Management? If so, tap it then look for installed profiles in Mobile Device Management. Tap the Profile > More Details > Mobile Device Management, then check to see if there is a passcode policy for the profile; let me know what you find.
Can you also let me know what type of email address you're using (iCloud, Gmail, Yahoo, etc.)?
Best Regards.