"Unable to Verify App. An internet connection is required to verify trust in the developer." This error appears when iOS tries to launch a sideloaded app, but can't complete the certificate validation handshake with Apple. Four causes account for almost every instance.

Cause 1: No internet on the device

iOS literally needs to phone home to verify the cert. If you're on a flight, in airplane mode, or on a network that blocks Apple's servers, verification fails.

Fix: Connect to Wi-Fi or cellular. Try a different network if a corporate firewall might be blocking ppq.apple.com or itunes.apple.com.

Cause 2: Certificate has been revoked

If Apple has revoked the certificate that signed the app, the verification call returns "invalid" and you get this error. Common for older Enterprise-signed apps.

Fix: The cert is dead — you need a re-sign with a fresh cert. See also: recovery from cert revoke.

Cause 3: Developer profile not trusted yet

For Developer/Enterprise-signed apps, you must explicitly trust the developer profile in Settings before iOS will run the app the first time. This error often shows up before you've done that.

Fix: See: how to trust an iOS developer profile. Settings → General → VPN & Device Management → [Developer name] → Trust.

Cause 4: Time/date wrong on device

Rare but real. If your device's clock is wrong (manually set, or after a battery-dead reset), certificate validation may fail because the cert appears not-yet-valid or already-expired.

Fix: Settings → General → Date & Time → Set Automatically.

Decision tree

  1. Is the device on the internet? → no → Cause 1
  2. Did the app work before for you and other users? → no, never worked → Cause 3 or 4
  3. Did the app work before and stop suddenly for everyone? → Cause 2 (revoke)
  4. Did the app stop only for you? → Cause 1 or 4

If the cert is revoked

You can confirm a revoke by checking if the app works on other devices. If it's dead everywhere, it's a revoke. Re-signing is the only fix.