Reboot after the compass calibration

What ArduPilot says:

• PreArm: Compass calibrated requires reboot

A compass calibration has been started since the flight controller was switched on. From that moment arming is refused until a reboot, so that the position estimator starts afresh with the new offsets. It does not matter how the calibration ended: finished, failed and cancelled all leave this message. This check cannot be skipped.

What to do, most likely first

1. A calibration was run and the flight controller has not been restarted since.

   FixReboot the flight controller: power off and on, or the ground station's reboot command. If the calibration did not end successfully, run it again first: a reboot alone keeps the old offsets.

The quick calibration where you type in the aircraft's heading (fixed yaw; “Large Vehicle MagCal” in Mission Planner) does not set this flag and asks for no reboot.

Where to do it:Setup & Tuning Guide