If you're experiencing issues with the KyBook app after updating iOS, you can follow these steps to troubleshoot and potentially resolve the problem:

1. Restart Your Device:
- Power off your iPhone or iPad completely and then power it back on to refresh the system.

2. Check for App Updates:
- Open the App Store, tap on your profile icon in the top-right corner, and scroll down to see if any updates are available for KyBook. If there is an update, install it.

3. Reinstall KyBook:
- Delete the KyBook app from your device by tapping and holding its icon until you see the 'Remove App' option, then select it.
- Reinstall it by searching for KyBook in the App Store and downloading it again.

4. Check iOS Compatibility:
- Ensure that the version of KyBook you have is compatible with your current iOS version. The app requires at least iOS 11 and should be on a 64-bit device. If you're using an older version, consider updating your app - learn more.

5. Adjust App Permissions:
- Go to Settings, scroll down to KyBook, and ensure it has the necessary permissions enabled, such as access to storage, iCloud, etc.

6. Clear Cache:
- In some scenarios, the app's cache can cause it to misbehave. While iOS doesn’t provide a direct way to clear app cache, deletion and reinstallation will help.

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