How to Trust Enterprise Developer Certificates on iPhone

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What Is an Enterprise Developer Certificate?

An enterprise developer certificate is a credential issued by Apple to qualifying organizations through its Apple Developer Enterprise Program. It allows those organizations to distribute internal iOS apps to their employees without going through the public App Store. Unlike standard individual developer certificates, enterprise certificates are not restricted to a specific list of device UDIDs — they can authorize installation on any device that trusts the certificate.

Third-party app installers like Scarlet iOS leverage this same enterprise certificate infrastructure to deliver apps to users. This is why you need to take an extra trust step: iOS does not automatically trust enterprise certificates the way it trusts App Store apps signed by Apple itself.

Why the “Untrusted Developer” Error Appears

When you first install an app signed by an enterprise certificate — including Scarlet iOS itself, or any app distributed through it — iOS displays an alert when you try to open it: “Untrusted Developer: iPhone has not trusted the software developer.” This is not an error in the traditional sense. It is a security checkpoint Apple builds into iOS to prevent enterprise-signed apps from running without explicit user consent.

Once you trust the certificate through Settings, the error goes away permanently for all apps signed by that certificate on your device. You only need to do this once per certificate.

Step-by-Step: How to Trust an Enterprise Certificate on iOS 18

Step 1: Install the App First

Complete the app installation normally. The app icon will appear on your home screen with a small warning indicator or it will open to the “Untrusted Developer” message when tapped. Either way, proceed to Step 2.

Step 2: Open Settings

From your iPhone home screen, tap the Settings app (the grey icon with gears).

Step 3: Navigate to General

Scroll down and tap General. This opens the general device settings section where Apple places certificate management alongside other device-level controls.

Step 4: Open VPN & Device Management

Within General, scroll down until you see VPN & Device Management (sometimes labeled simply as Device Management on older iOS versions). Tap it. This screen lists all configuration profiles, MDM enrollments, and enterprise developer certificates currently installed on your device.

Step 5: Find the Certificate

Under the Enterprise App section, you will see one or more entries. Look for the certificate associated with the app you are trying to trust — this will typically show the name of the signing organization. Tap on that entry to open the certificate detail page.

Step 6: Tap Trust

On the certificate detail page, you will see the organization name, the certificate type, and a blue Trust “[Organization Name]” button. Tap it. iOS will display a confirmation dialog warning you that trusting this certificate allows all apps signed by this developer to run on your device. This is expected and intentional. Tap Trust again to confirm.

Step 7: Return to Your Home Screen and Open the App

Press the Home button or swipe up to return to your home screen. Tap the app icon. It should now open without any “Untrusted Developer” message. If you are trusting the Scarlet iOS installer itself, it will launch and you can immediately begin installing other apps.

Trusting Certificates for Apps Installed Through Scarlet iOS

When you install an app through Scarlet iOS, that app is signed by the same enterprise certificate used by Scarlet iOS itself. This means that once you trust the Scarlet iOS certificate, all apps installed through the platform should also be trusted automatically — you typically do not need to repeat the trust process for each individual app.

However, if Scarlet iOS rotates to a new certificate (which happens periodically as part of its certificate renewal system), apps signed under the new certificate will require a fresh trust action. Scarlet iOS typically alerts you when this happens and walks you through the re-trust process with a prompt inside the app.

What If the Certificate Is Not Visible in Settings?

If you navigate to VPN & Device Management and do not see any enterprise app certificate listed, it means the configuration profile was not successfully installed. Go back and repeat the profile installation step from the beginning. Make sure you are using Safari (not Chrome) and that you tapped Allow when iOS prompted you to permit the profile download. For a full reinstallation walkthrough, see how to install Scarlet iOS on iPhone without a computer.

Certificate Revocation: What It Means and What to Do

Apple monitors enterprise certificate usage. When it detects a certificate being used for broad public distribution — as is the case with Scarlet iOS — it may revoke that certificate. A revoked certificate means that all apps signed with it will stop launching on all devices simultaneously, regardless of whether those devices have trusted the certificate previously.

When this happens:

  • Existing apps installed through the revoked certificate will show an error on launch.
  • No new apps can be installed using the old certificate.
  • The Scarlet iOS team will issue an update with a new certificate as quickly as possible.
  • You will need to reinstall Scarlet iOS using the new certificate and re-trust it in Settings.
  • You may need to reinstall apps that were signed under the old certificate.

This is the single most disruptive part of using enterprise-certificate-based sideloading. Scarlet iOS’s automatic certificate renewal system minimizes the frequency and impact of revocations, but they cannot be eliminated entirely. For help when things go wrong, the Scarlet iOS not working — 10 fixes guide covers certificate revocation recovery in detail.

Tips for Managing Multiple Certificates

  • Periodically review your VPN & Device Management screen and remove certificates from apps or services you no longer use.
  • If you use multiple sideloading platforms, each may use a different enterprise certificate. Trust each one individually.
  • Do not trust certificates from sources you do not recognize or have not deliberately installed. Unfamiliar certificates in your list may indicate a compromised or unknown app installation.

Getting Started with Scarlet iOS

Trusting an enterprise certificate takes under a minute and unlocks a world of apps beyond the App Store. With the trust step complete, Scarlet iOS and every app it delivers will run seamlessly on your iPhone or iPad.

Ready to get started? Visit Scarlet iOS and install it today. The trust process is the only technical step in an otherwise seamless experience.

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