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You see this: The helper’s log on the iPhone ends with Failed to initialize for UI testing: ... Timed out while enabling automation mode. Mobster shows On your iPhone, turn on Settings › Developer › Enable UI Automation instead.

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Why it happens

Before it starts UI automation, iOS waits for the passcode unless Enable UI Automation is on. The wait ends after 60 seconds, and the helper doesn’t start. In the run recorded for this page (14 Oct 2026), the failure came 60 seconds after Running tests....

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Fix

  1. On the iPhone, open Settings › Developer and turn on Enable UI Automation. If iOS asks for the passcode, enter it.
  2. Keep the phone unlocked while the helper starts.
  3. Start the helper again from Mobster for Mac, or run mobster serve --manage-device. It starts by itself about 2 seconds after iOS turns automation mode on.

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Check it worked

The helper answers at http://127.0.0.1:8100, and mobster doctor prints ✓ WebDriverAgent. Once the switch is on, iOS stops asking. Checked 26 Oct 2026 against Mobster 0.4.0. Back to Troubleshooting.