Software Update Failed An error occurred downloading iOS 15.7.

Hi sinesh192,

Thanks for coming to Apple Support Communities for help today.

We can point you to some steps that may resolve this issue for you, however, we'd also advise having a stronger Wi-Fi connection than is shown in your screenshot the next time you attempt to update.

Check out this article: If your iPhone or iPad won't update.

For that particular error message, these steps will help.

"Try updating your device again using the same network. If you still see one of these messages, try updating your device using another network or update your device with your computer:

• Update your device using a Mac with macOS Catalina or later
• Update your device using a Mac with macOS Mojave or earlier, or a Windows PC

If the issue happens again after trying to update with multiple networks, remove the update."

You can also remove the update using these steps and start over again:

"If you still can't install the latest version of iOS or iPadOS, try downloading the update again:

1. Go to Settings > General > [Device name] Storage.
2. Find the update in the list of apps.
3. Tap the update, then tap Delete Update.
4. Go to Settings > General > Software Update and download the latest update."

Have a fantastic day!