I couldn’t download ios 14.8 in my iPhone7plus. It’s showing that “ Software update failed. An error occurred downloading ios 14.8.”

Hi risha242,

We understand you're unable to download an update on an iPhone. We're happy to help.

If you're unable to download an update directly on the device, you can try these steps: If your iPhone, iPad or iPod touch won’t update

If you're still unable to download the update directly on the device, you'll need to install it through a computer instead.

If you're using a Mac: Update your iPhone, iPad, or iPod touch with the Finder

If you're using a Windows PC: Update software on iPhone, iPad, or iPod touch in iTunes on PC

As always make sure you have a current backup of the device before installing an update on it. If you have not yet backed up the device make sure to do that first before making any further update attempts.

How to back up your iPhone, iPad, and iPod touch

Hope this helps. Cheers!