Frequently asked questions #

Why does my device not or fail to pair? #

This problem can be divided in 2 categories; no logging is shown at all OR interview fails.

No logging is shown at all #

Interview fails #

How do I migrate from a CC2531 to a more powerful coordinator (e.g. ZZH)? #

Since Zigbee2MQTT 1.21.0 this can be done without having to repair all devices. Stop Zigbee2MQTT, plug in the new coordinator and update the serial -> port in your configuration.yaml, next start Zigbee2MQTT.

How do I move my Zigbee2MQTT instance to a different environment? #

Details about your network are stored in both the coordinator and files under the data/ directory. To move your instance to another environment move the contents of the data directory and update the path to your coordinator in your configuration.yaml. Now you can start Zigbee2MQTT.

What does and does not require repairing of all devices? #

Requires repairing #

You need to re-pair all you devices when:

Doesn’t require repairing #

You don’t need to re-pair your devices when:

No worry, in case it happens with end devices (battery powered) it most of the times does not mean the devices aren’t connected to the network map anymore. Some end devices (e.g. Xiaomi door sensor) sleep for a too long time which causes the parent (router child ageing) to remove it from it from its child table. This is what causes the missing link. Even while its not in the child table anymore, the end device can still communicate via the router. This does not always happen since not all routers use child ageing (this is a Zigbee 3.0 feature).

Why is the action property always empty? #

When the Home Assistant integration is enabled (homeassistant: true in your configuration.yaml) the action property of your e.g. buttons will almost always be empty. Whenever an action is published e.g. {"action": "single"} it will be immediately followed up by a {"action": ""}. This is to trigger a state change in the Home Assistant action sensor (so that it can be used in e.g. automations).

Help, Zigbee2MQTT fails to start! #

Most of the times this is caused by zigbee-herdsman not being able to communicate with your adapter (e.g. CC2531).

Error: SRSP - SYS - ping after 6000ms #

2 common reasons of this error:

  1. The port of your serial adapter changed. Check this to find out the port of your adapter.
  2. If you are using a CC2530 or CC2531; it is a common issue for this adapter to crash (due to its outdated hardware). Reflashing the firmware should fix the problem. If it happens often consider upgrading to a more powerful adapter.

Verify that you put the correct port in configuration.yaml #

Execute the following command to find out the correct path:

pi@raspberry:/ $ ls -l /dev/serial/by-id
total 0
lrwxrwxrwx. 1 root root 13 Oct 19 19:26 usb-Texas_Instruments_TI_CC2531_USB_CDC___0X00124B0018ED3DDF-if00 -> ../../ttyACM0

In this example the correct port would be /dev/ttyACM0.

Verify that the user you run Zigbee2MQTT as has write access to the port #

This can be tested by executing: test -w [PORT] && echo success || echo failure (e.g. test -w /dev/ttyACM0 && echo success || echo failure).

If it outputs failure it could mean your user does not have access to the port. To test assign write access by executing: sudo chown [USER] [PORT] (e.g. sudo chown pi /dev/ttyACM0).

if it outputs failure, then you need to permanently give your user permission to the device.

Method 1: Give your user permissions on every reboot. #

You can create a ‘udev’ rule yo give your user permissions after every reboot:

  1. udevadm info -a -n /dev/ttyACM0 | grep 'serial' get the serial to your device YOURSERIAL

  2. Create the rule file with: sudo nano /etc/udev/rules.d/99-usb-serial.rules

  3. add this line: SUBSYSTEM=="tty", ATTRS{idVendor}=="0451", ATTRS{idProduct}=="16a8", ATTRS{serial}=="YOURSERIAL", SYMLINK="ttyUSB.CC2531-01", OWNER="pi"

  4. modify your Zigbee2MQTT config to adjust new SYMLINK name: nano /opt/zigbee2mqtt/data/configuration.yaml

… serial: port: /dev/ttyUSB.CC2531-01 …

After reboot your device will have the right permissions and always the same name.

Method 2: Add your user to specific groups #

As mentioned on , depending on your linux installation, various groups could have ownership of the device.

Add your user to the uucp , tty , dialout groups:

sudo usermod -a -G uucp $USER
sudo usermod -a -G tty $USER
sudo usermod -a -G dialout $USER

Reboot your device and now your user should have access to the device.

Error: Coordinator failed to start, probably the panID is already in use, try a different panID or channel #

Error: Resource temporarily unavailable Cannot lock port #

This error occurs when another program is already using (and thus locking) the adapter. You can find out which via the following command: ls -l /proc/[0-9]/fd/ |grep /dev/ttyACM0 (replace /dev/ttyACM0 with your adapter port).

Raspberry Pi users: use a good power supply #

A bad power supply can make your system and its USB devices unstable. Make sure to use a good power supply.

In case you see message like below when running dmesg -w you are using a bad power supply.

[44870.355590] Under-voltage detected! (0x00050005)
[44874.515618] Voltage normalised (0x00000000)
[44880.755718] Under-voltage detected! (0x00050005)
[44889.075627] Voltage normalised (0x00000000)

When you have a SSD connected to the Pi, try connecting the adapter via a powered USB hub.

Make sure the extension cable works #

A bad extension cable can lead to connection issues between the system and the adapter. Symptoms of this are disconnection messages in the dmesg -w log like below.

[44929.156957] usb 1-1.5: USB disconnect, device number 119
[44929.455555] usb 1-1.5: new full-speed USB device number 120 using dwc_otg
[44929.604582] usb 1-1.5: New USB device found, idVendor=0451, idProduct=16a8, bcdDevice= 0.09
[44929.604596] usb 1-1.5: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[44929.604606] usb 1-1.5: Product: TI CC2531 USB CDC
[44929.604615] usb 1-1.5: Manufacturer: Texas Instruments

For Openhab users: disable zwave binding #

The Openhab zwave binding interferes with Zigbee2MQTT, click here for more information.

In case of a CC2530 or CC2531 adapter, verify that don’t have a CC2540 #

The CC2540 can be confused easily with the CC2531 as it looks (almost) exactly the same. However, this device does not support zigbee but bluetooth. This can be verified by looking at the chip.

ModemManager is installed #

ModemManager, which is default installed on e.g. Ubuntu, is known to cause problems. It can easily be fixed by removing ModemManager through sudo apt-get purge modemmanager.

[hciuart] is running #

hciuart can be disabled by executing: sudo systemctl disable hciuart.

CC1352P-2/CC26X2R1 launchpad coordinators only: press the reset button on the device #

If Zigbee2MQTT fails to start with a CC1352P-2 with Error: SRSP - SYS - version after 6000ms, you most probably have connected your device to a system that requires pressing the reset button (the one next to the USB connector) momentarily/shortly after connecting the USB cable. This issue has primarily been observed on x86 architectures only (e.g., Intel NUC, HPE Microserver, i7 laptop), see also #2162. The procedure has to be repeated every time the CC1352P-2 is re-connected and it’s not clear yet, whether this can be fixed at all. It does not seem to occur on ARM based boards (Raspberry Pi, ODROID XU4).

Something that can also solve the issue is to replug the USB cable.

CC2531 coordinators only: press the reset button on the device #

When you plug the CC2531 in your computer, the green LED should go on. By pressing the reset button on the CC2531 the green LED should go off. The CC2531 has 2 buttons on it, the reset button is the one which is closest to the USB port. Now try starting Zigbee2MQTT again.

CC26XR1 LaunchPad coordinators only: verify that you have the correct revision #

The revision of your board can be seen in UniFlash by clicking more info in the top, now press Read device info.

The correct revision is: E like shown below.


All earlier version are not supported (these are development boards). Return this board to the seller immediately.

I read that Zigbee2MQTT has a limit of 20 devices (when using a CC2531), is this true? #

Definitely not! Example given: the default Zigbee2MQTT CC2531 firmware indeed supports 20 devices connected directly to the coordinator. However, by having routers in your network the network size can be extended. Probably all AC powered devices e.g. bulbs serve as a router, you can even use another CC2530/CC2531 as a router (which has a limit of 21 devices).

Example #

When using the default Zigbee2MQTT CC2531 coordinator firmware + 2 CC2531 routers your device limit will be:

Which port should I use for CC26X2R1/CC1352P-2, /dev/ttyACM0 or /dev/ttyACM1? #

The CC26X2R1 has a build in debugger. This debugger also registers a port next to the device data port. Of course this is not necessarily number 0 and 1. But normally the lowest number is the device data port and the other the debugger.

To find the correct port, execute:

pi@raspberry:/ $ ls -l /dev/serial/by-id
total 0
lrwxrwxrwx 1 root root 13 Jan  6 19:07 usb-Texas_Instruments_XDS110__03.00.00.05__Embed_with_CMSIS-DAP_L1100BTD-if00 -> ../../ttyACM0
lrwxrwxrwx 1 root root 13 Jan  6 19:07 usb-Texas_Instruments_XDS110__03.00.00.05__Embed_with_CMSIS-DAP_L1100BTD-if03 -> ../../ttyACM1

The device with id ending with if00 is for device data. Use this port in your configuration.

Common error codes #

A list of common error codes and what to do in case of them:

How do I run multiple instances of Zigbee2MQTT? #

In case you setup multiple instances of Zigbee2MQTT it’s important to use a different base_topic and channel. This can be configured in the configuration.yaml.