Sometimes, when updating iOS 16, you may encounter various update errors, such as the "Unable to verify update" error on your iPhone when installing iOS 16.
Don't worry, in this post, I'll share you how to fix iPhone Won't Update to iOS 16 in 5 ways.
Method 1: Use the professional iPhone repair tool

Step 1: Download and install iSunshare repaire genius for free on your computer and upgrade iTunes to the latest version.
Step 2: Run the software and click on the "Standard Mode" option.
Step 3: Follow the software prompts to the download firmware package page and click on "Download" to download the firmware package.
Step 4: Once the firmware package has been verified, click on the "Repair" button and your iPhone will immediately begin to fix the failed iOS update.
Soon, the software will tell you that your iPhone has been successfully repaired and your iPhone will be updated to the latest version of iOS.
Method 2: Check if your device supports iOS16
If the device is not compatible with iOS 16, you may receive a message that the update cannot be installed. You will need to ensure that the device is on the supported list for iOS16.

Method 3: Free up iPhone storage space
iOS updates take up a lot of storage space, and a lack of memory may cause the update to fail. Follow the path [Settings] - [General] - [iPhone Storage] to check your iPhone's storage space usage.
Method 4: Delete the updated firmware package
If your network is unstable during the download of the update package or for other reasons the downloaded installation package is not a complete file, then you need to delete the update package.Open [Settings] - [General] - [iPhone Storage], find the "Updates" option in the list of applications and click on it, then "Delete Updates" file.
Method 5: Force restart iPhone
When the device has basic iOS faults such as stuck, frozen, black screen, etc., try the forced reboot method to fix them all.Different iPhone models have different force restart buttons, you can find the latest instructions on Apple's website.