Unable to arm, but no error messages

I am using DJI f450 and 3DR pixhawkMINI. The software I am using is beta 3.5-rc1 here: http://firmware.us.ardupilot.org/Copter/beta/PX4/ArduCopter-v2.px4. When I finished the calibration, it just does not let me arm and there is no error message. Any potential reasons?

I am having this issue as well, except I am using a Solo 3DR, and I am not on the beta version.

Without logs it’s going to be hard to know what’s going on.

There are 2 areas that might give answers.
Using Mission Planner Flight Data/Messages tab you should see all the messages from the PH, even if they do not appear in red on the HUD. Not all messages display on the HUD.
Set Log_Prearm to true and you will get logging from power up. This might shed some light on whats going on.

If it is not arming there is, in my experience, always some message telling you why.

Thanks for your reply! The problem is, there is no error message at all, neither in the messages tab or displayed in the HUD. APM Planner shows that the drone is armed, and I get SUCCESS: Executed CMD: 400 in the Messages tab under Flight Data.

The strange thing is that when I tried to disarm from APM planner (I had armed inside APM Planner as well), I get FAILURE: Unsupported CMD: 400.

Also, I consistently get EKF primary changed: 0, followed by it changing to 1 as well. Not sure why I am getting that message.

EDIT: I will upload the log shortly.
Edit2: Log uploaded. The date shown on the log obviously is wrong.99-12-31_19-53-26_1.bin (1.4 MB)

@lroberts your log shows some strange RC input values.
Have you calibrated your RC?
Have you checked that you have the right channels amps to the right inputs?
Have you checked that they are not reversed?

@mboland I am using a 3DR Solo and 3DR controller. I am not aware of any calibration necessary for the 3DR controller, perhaps I’m missing something? Thanks.

@lroberts I think I see the problem.

What firmware have you installed?

The standard release firmware in Mission Planner is not Solo compatible.
That will be your problem if thats what you installed.

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In Mission Planner or APM Planner ‘‘Disable Arm Check’’

For connection with wire only to Mac or Pc Have No Solution.

I use the APM2.8