Many devices prevent downloads if your battery is below 50% to ensure the device doesn't die mid-installation.

Modern updates can be several gigabytes. If your drive is nearly full, the device simply won't have room to stage the new files.

If your phone is refusing to pull the latest firmware, try these steps in order: If your iPhone or iPad won't update - Apple Support (CA)

Getting a "cannot download software update" notification is a common but frustrating experience that can leave your device vulnerable to security threats or missing out on new features. Whether you’re on a smartphone or a computer, the cause is usually one of a few usual suspects: poor connection, low storage, or a temporary software glitch. Why Software Updates Fail to Download

Before diving into fixes, it helps to understand why the download is stalling:

Updates require a steady internet signal. Even a momentary drop can cause the entire package to fail verification.

When a major update launches (like a new iOS or Windows version), millions of people try to download it at once, which can overwhelm the manufacturer's servers. How to Fix Update Issues on Mobile (iPhone & Android)