Standby mode bug after updating to iOS 18

If that happened to me, I would try:

Settings > General > Transfer or Reset iPhone > Reset > Reset All Settings.

That should fix it. If not, I would do this next:

Force Restart iPhone - Apple Suport

"Standby mode bug after updating to iOS 18: standby mode bug: Hello I’ve been having this weird glitch since iOS 18 and tried downloading ios26 to fix it but it didn’t work I looked for answers online and found nothing :( is it even possible to fix it?"

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Thank you for the screenshot.

Before trying a reset, try the following...

A. Reset the Home Screen Layout...

Go down to one Home Screen, and then reset it Home Screen Layout:

1. Go Here: Move and organize apps on iPhone - Apple Support
2. Scroll to: Reset the Home Screen and Apps to their Original Layout
3. Go to: Settings
4. Tap: General
5. Tap: Reset
6. Tap: Reset Home Screen Layout

B. Updating and iPhone:

I see "iOS 26" is shown as your iOS. So, if you are actually on iOS 18, and cannot successfully perform an update installation, then you should try updating the iPhone using a computer or Cellular, for your model. Be certain you have the services, if you decide to follow through with Cellular. Use my User Tips:

• Computer: Update your iPhone Using a Computer - User Tip
• Cellular: Use an iPhone 12 or later, that is using 5G, in order to update over Cellular - User Tip

"Standby mode bug after updating to iOS 18: None of them worked :("

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To the OP and All those Affected...

This seems to be catching on. So,...

Report this to Apple:

Do your Part: Provide Apple with feedback on this, letting them know about this issue.  Apple may not get back to you directly, but the more feedback they receive on this, the more they will know what is occurring, and what bug fixes to include in updates to come. Apple will know nothing of this, if you don't report it to them.

1. Go Here: Feedback - iPhone - Apple
2. Select: "Bug Report" for the "Feedback Type"
3. Comment: that this all began after installing an update. Include the URL of this thread.
4. Proceed from there as necessary

Thank you for the screenshot.

"Standby mode bug after updating to iOS 18: None of them worked :("

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Thank you for the screenshot.

Then it probably comes down to a Factory Reset, as provided by sberman. But, a few things to try, before doing so.

A. Start with a Force Restart:

Go Here: Force Restart iPhone - Apple Support

B. Getting Out of a Boot Loop:

If stuck after an update, and is continually restart, if is stuck in a Boot Loop. Use my User Tip: How to Fix an iPhone in a Boot Loop - User Tip

C. Provide a Photo of your Computer Screen:

Are you seeing any messages on your Mac or Windows PC when attempting this update through your Mac? If so, a screenshot may help. Black out personal info (i.e. Time and Names) through use of the Photos app on your Mac.

D. Turn Off All VPNs:

Do you have any VPNs Turned on? IF so, turd them off as the get in the way through configurations.

E. Use a Private LAN:

When updating, it is best to update through Private LAN (Local Area Network), likely that of your home.

F. Use Ethernet:

If you update through you computer, try connecting through Ethernet, if available. IF you have no adapter on your computer, you would need an adapter, plugging your Mac or PC into your router/modem.

G. Try Another User:

For troubleshooting purposes, create a new Administrator user. Log into it, and attempt the update, using the above, if needed. Trash this user, after after the updates has completed.