Copter falls immediately after switching on autotune

Hello My configuration is: F450 frame clone, Arducopter 2.6, sunnysky x2212, 30A esc XXD HW30, 1045 prop, zippy 5000mAh 30C, 1770 g. Log is attached

It looks like you were in stabilize. I understand that you would need to select altitude hold before engaging autotune. Even so, it looks like a motor stopped and caused it to roll right and slightly to the rear as she fell.

Before turning autotune I switched to althold, but it was only a few seconds …

I’ve been through this. I’d suggest you start with making a bench test on every motor to see if you have any sync issues. When the firmware does an autotune it goes from almost no throttle to a lot of it in an instant. If the motors don’t keep up then they fall out of sync and normally results in that they just stop spinning which you understand of course is not good and causes the craft to fall like a stone.
To bench a motor you could do the following in this exakt order

  1. Remove all servo leads from the motors you are not going to bench and preferably the blades from these motors as well.
  2. Set the flightmode to “ACRO” so no auto balancing is done
  3. Hold down the craft and make sure the blade is no way near your arm
  4. ARM the copter (now this blade should be moving, all others off)
  5. Punch the throttle from “off” all the way to the top and see the reaction of the motor. Do this several times repeatedly to see if it consequent
  6. Do the same for the other motors

The outcome should be that the motor spins up with no problems. If you have a sync issue the motor will stall or just stop until you lower the throttle again.
You have to do this with the prop on or else there will be no load to generate the behaviour

You don’t have many logs enabled. Can you try again with RCIN, RCOUT and IMU might help too.

Is it the moment you switch or the moment it starts to roll when it starts doing its thing? if the latter philsson test is valid. If when switching before its starts its dance its something else.