I can’t install the new update after I finished downloading it. It’s says “An error occurred installing iOS 14”. What Can I do ?

First Toggle OFF Battery Low Power Mode and try to install the iOS 14 update again!

Goto Settings > Battery > Low Power Mode -> OFF

If it doesn't work, delete the iOS 14 upgrade file (maybe it is corrupted)

1. Go to "Settings > General" on your iPhone.
2. Select "iPhone Storage".
3. All the apps will be listed there, including the iOS software update.
4. Click on the iOS update and tap "Delete Update" to confirm.

Then go back and try to download/install iOS 14 again!

Go to Settings > General > Software Update.

Hi, you can also update your phone via iTunes or on a macbook.

You can check this: Update your iPhone, iPad, or iPod touch