Guide: Troubleshooting arming issues

Quad is not arming, what should I do?

Starting from Betaflight 3.2 (and above), pilot can get more detailed troubleshooting information on the reasons why the craft will not arm via:

  • the CLI
  • beep patterns
  • Betaflight OSD
  • Betaflight Configurator

Information about the reasons why craft is not arming is called arming prevention flags. Below you can find the detailed description of the each method.



One of the easiest ways to check the reason while the quad is on the bench. Just connect the flight controller to the configurator, enter the CLI mode and issue status command. The last line of the status info is arming prevention flags list:

Notes: Refer to the table below for the detailed flags meaning. Arming prevention flags in status command works only from BF version 3.2 and up.

Beep patterns

If your craft has a beeper connected to the flight controller it will emit a warning signal indicating the most important (lowest number) reason why arming is disabled.

The signal is as follows:

  • five short ‘attention’ beeps;
  • a number of long beeps (may be 0);
  • a number of short beeps with long intervals (may be 0).

The arming prevention condition that is active can be calculated as (5 * <number of long beeps>) + <number of short beeps>. For example:

  • 1 long and 2 short beeps = 7
  • 2 long beeps = 10


Betaflight OSD

You can see the arming prevention flags right on your OSD screen. Put “Warnings” element on the OSD layot and it will indicate you why craft won’t arm. OSD Warnings element can be enabled from the “OSD” tab:


Betaflight Configurator

You can also see the Arming Disable Flags in the first configuration tab “Setup”. Notice that it will only show the most important one. This is the same value as the beeper indicates in the case of the arming prevention.


Most common reasons that prevent from arming

  • Flight Controller is not receiving/recognizing the signal from RX (flag name: RX LOSS).
  • Throttle channel is too high. Check if the throttle stick is at the lowest possible position.
  • Craft is not level (enough) (flag name: ANGLE). Level craft to within small_angle degrees. The default is 25 degrees. 
  • Starting from Betaflight version 3.30 arming is  disabled when the flight controller is connected to the Betaflight configurator (flag name: MSP and CLI). This was added in order to keep users from accidentally arming their craft when testing their RX / mode switches with a battery connected. In order to enable arming for bench testing, go to the ‘Motors’ tab and enable the ‘Motor test mode’ switch (REMOVE ALL PROPELLERS FIRST);


CLI/Beep codes and arming prevention flags list table

Name Description Beep code Required Actions
3.2 3.3 3.4/3.5 4.0+
NOGYRO A gyro was not detected 1 1 1 1 You may have a hardware failure, if a previous firmware version works then it may be a firmware issue.
FAILSAFE Failsafe is active 2 2 2 2 Rectify the failure condition and try again.
RX LOSS(1) No valid receiver signal is detected 3 3 3 3 Your receiver is either faulty or has no link to the transmitter.
BAD RX(1) Your receiver has just recovered from receiver failsafe but the arm switch is on 4 4 4 4 Switch the arm switch off.
BOXFAILSAFE The ‘FAILSAFE’ switch was activated 5 5 5 5 See FAILSAFE
RUNAWAY Runway Takeoff Prevention has been triggered   6 6 6 Disarm to clear this condition.
THROTTLE Throttle channel is too high 6 7 7 7 Lower throttle below min_check.
ANGLE Craft is not level (enough) 7 8 8 8 Level craft to within small_angledegrees (default 25).
BOOT GRACE Arming too soon after power on 8 9 9 9 Wait until pwr_on_arm_graceseconds (default 5) have elapsed.
NO PREARM Prearm switch is not activated or prearm has not been toggled after disarm 9 10 10 10 Toggle the prearm switch.
LOAD System load is too high for safe flight 10 11 11 11 Revisit configuration and disable features.
CALIB Sensor calibration is still ongoing 11 12 12 12 Wait for sensor calibration to complete.
CLI CLI is active 12 13 13 13 Exit the CLI.
CMS CMS (config menu) is Active – over OSD or other display 13 14 14 14 Exit the CMS (or OSD menu).
OSD OSD menu is active 14 15 15   Exit OSD menu.
BST A Black Sheep Telemetry device (TBS Core Pro for example) disarmed and is preventing arming 15 16 16 15 Refer to the manual for your hardware.
MSP MSP connection is active, probably via Betaflight Configurator 16 17 17 16 Terminate the Betaflight Configurator connection (disconnect).
PARALYZE Paralyze mode has been activated     18 17 Power cycle/reset FC board.
GPS GPS rescue mode is configured but required number of satellites has not been fixed     19 18 Wait for GPS fix or disable GPS rescue mode.
RESCUE SW GPS Rescue switch is in an unsafe position       19 Turn off the GPS Rescue switch to arm.
RPMFILTER(2) Motor RPM-based filtering is not functioning       20 One or more ESC’s are not supplying valid RPM telemetry.
ARMSWITCH Arm switch is in an unsafe position 17 18 20 21 Toggle the arm switch to arm.

(1) This may appear on the Betaflight OSD during flight, take it as a sign that your radio system is either faulty or you are flying at the edge of your range. Treat it the same you would an “RSSI critically low” warning.

(2) RPM-based filtering is enabled but one or more ESC’s are not supplying valid DSHOT telemetry. Check that the ESC’s are capable of and have the required firmware installed to support bidirectional DSHOT telemetry.

Most up to date ARMING_FLAG list can be found in the current BetaFlight source code:



Parts of this article taken from Betaflight Wiki
2018-05-31 article created
2019-03-19 updated table to betaflight 4.0 

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