> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mobster.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Failed Registering Bundle Identifier

> Another team already owns the helper's app ID. Build again and Mobster gives the helper an ID of your own.

You see this: `xcodebuild` prints `Failed Registering Bundle Identifier: The app identifier "app.mobster.wda.runner" cannot be registered to your development team because it is not available.` Mobster shows `The helper's app ID is taken by another team.`

## Why it happens

App IDs are unique across Apple. The default one for the helper belongs to a different team, so yours can't register it.

## Fix

1. Install the helper again from Mobster for Mac. It picks an app ID made for your team.
2. If it fails again, open Xcode › Settings › Accounts, check the team and build once more.

## Check it worked

The build finishes and `mobster doctor` prints no `✗` line for the runner.

Checked 26 Oct 2026 against Mobster 0.4.0. Back to [Troubleshooting](https://docs.mobster.dev/troubleshooting.md#iphone).


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