Can't Install an App on an iOS Device? Here's What to Check

Installing apps on iOS devices can sometimes be a frustrating experience, as Apple doesn't provide clear error messages. Here's a guide to help you troubleshoot common installation issues.

Common Installation Problems

The iOS Install Popup Didn't Appear

If the "Loadly.io would like to install..." popup didn't appear after tapping the "Install" link, check if the same app is already installed from the App Store. iOS 8 and later prevent you from overwriting an App Store app with a different version.

To fix this, delete the app installed from the App Store, then try installing the test version from Loadly.io.

Nothing Happened After Tapping "Install"

If the popup appeared but nothing seemed to happen after tapping "Install", check your device's home screen. iOS 8 and later install apps silently in the background, so the app icon may already be on your home screen with a progress indicator.

"Untrusted Enterprise Developer" Popup

On iOS 9 and later, you need to trust the Enterprise developer profile in your device's Settings before you can use an in-house Enterprise app.

"Unable to Download App" Popup

This usually indicates an issue with your internet connection or a firewall blocking the app's .ipa file. Common causes include:

Expired provisioning profile
Device UDID not in the provisioning profile
Incompatible device (wrong iOS version, device family, or required capabilities)

Tips for Developers

If you're a developer and can't install your app on some devices, here are a few things to check:

The device's UDID must be included in the provisioning profile used to build the app.
The device's UDID must not start with "fffffff..." (which indicates a fake UDID).
You're building a Release version of the app, not a Debug version.
The device isn't behind an enterprise firewall that's preventing app installation.

You can also try installing the app by dragging and dropping the .ipa file into iTunes and syncing your device. If that doesn't work, the app may not be valid.

More Detailed Explanations

UDID Requirements

For Development or Ad-hoc builds, the device's UDID must be added to the provisioning profile used to sign the app. Enterprise builds don't require registering UDIDs.

You can find the embedded provisioning profile in the .ipa file by unzipping it and looking for the embedded.mobileprovision file.

Valid UDIDs

A valid UDID is a 40-character hexadecimal string (e.g., 37149a037f1..................................3c0078). Avoid "fake" UDIDs starting with "ffffff...", as those are not valid.

You can retrieve a valid UDID using iTunes, the Finder on a Mac, or a web app like Loadly.io.

Built Architectures

When building iOS apps, you can target different architectures (armv6, armv7, arm64) (Source: List of iOS devices on Wikipedia). In Debug configuration, Xcode may only build for the "current" architecture, which could prevent the app from running on other devices.