Tailsitter and tiltrotor are both enabled

What ArduPilot says:

• PreArm: set TAILSIT_ENABLE 0 or TILT_ENABLE 0
• Config Error: set TAILSIT_ENABLE 0 or TILT_ENABLE 0

Q_TAILSIT_ENABLE and Q_TILT_ENABLE are both above 0. A tailsitter takes off standing on its tail and pitches its whole body forward to fly on the wing; a tiltrotor keeps its body level and swivels its motors forward. An aircraft is one or the other. At power-on this is a “Config Error” repeated every 5 s while the board does nothing else; set after start-up, it stops arming.

What to do, most likely first

1. One of the two was switched on by ArduPilot itself, from other parameters.

   CheckAt start-up, if it was never set by hand, Q_TAILSIT_ENABLE becomes 1 when Q_FRAME_CLASS is 10 or Q_TAILSIT_MOTMX is not 0, and Q_TILT_ENABLE becomes 1 when Q_TILT_MASK is not 0 or Q_TILT_TYPE is 3.

   FixSet the one that is not your airframe to 0, clear the parameter that switched it on (Q_TILT_MASK or Q_TAILSIT_MOTMX), and reboot.

2. The parameters were loaded from a file made for a different kind of VTOL.

   CheckParameter Compare & Migrate shows what the file changed.

   FixDecide which of the two the aircraft is, set the other enable parameter to 0, and reboot.

A tailsitter whose motors tilt a little for control (vectored thrust) is still a tailsitter: Q_TILT_ENABLE stays 0.

Parameters to look at

Where to do it:Parameter Compare & Migrate