Hello everyone,
I have the message “error compass variance” when using the sitl with gazebo.
Any idea ? 
Hi @sarah_gress, please don’t post the same question multiple times. This post has an almost identical question: SITL : my rover doing toilet bowl.
The most likely issue is that the model is not set up correctly and is not staying still long enough to initialise the gyros and magnetometer. This could be the SDF model joint parameters, the PWM scaling in the control blocks of the ArduPilot plugin, the AP params for the steering or throttle rate controllers or a number of other things.
Without the model and its AP parameters it’s not possible to diagnose what might be going wrong.