iPhone says “Untrusted Enterprise Developer”

This is not an error but iOS asking whether you trust this developer. You answer once — after that all apps from it open.

What to do

1. Open device management. Settings → General → VPN & Device Management.
2. Choose the developer profile. Under Enterprise App or Developer App, tap the name.
3. Tap Trust. Confirm, then open the app again.

Still not working?

No VPN & Device Management section or no profile in it — message us and we will check the certificate.