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You see this: xcodebuild prints error: unable to open output file ... 'No space left on device' while it compiles the helper.

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Why it happens

The build writes to Mobster’s wda-build folder in ~/Library/Application Support/app.mobster.desktop/. Xcode stops when the disk has no room.

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Fix

  1. Free up space on your Mac.
  2. Build again from Mobster for Mac.

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Check it worked

mobster sim doctor prints a Free space line with the room left. Checked 26 Oct 2026 against Mobster 0.4.0. Back to Troubleshooting.