No live wrist HR after update 21.20

In case you haven't done it yet, switch the watch off and on again. Are the LEDs on the back of the watch on? If not, maybe a power mode that disables the OHR sensor was accidentally enabled?

Check your sensors version. 

Check it in:

System > About > 6 times DOWN button 

If any of the versions is equal to 0.0.0 or 0.0, your update wasn’t finished correctly.

Did reboot yesterday but did not work. The lights are not turning on from the sensor. As linsguilherme asked below two sub versions bmx and ohr are standing on 0.0.0 and 0.00.00. so for some reason the update failed. What are the next steps?

Hey you are right for some reason BMX and OHR are standing on 0.0.0 and 0.00.00. What can i do next to get it working again?

Hey oBuTTuSo this seems to have resolved the issue. Thank you so much. Merry Xmas and a happy new year 

I have the same issue. Today in the morning I updated my Forerunner 955 to version 21.20 and after it HR sensor stopped working.

I see only "--".

In About section BMX and WHR version are set to 0.0.0 and 0.00.00. I performed "Software reinstall" as suggested but it didn't help.

Do you have any idea what else I can do?

Unfortunately not, the tip of oBuTTuSo helped me out.

If it worked before the update and now has the 0.0.0 version issue, the probable cause is the software.

If reinstalling the software doesn't help, contact Garmin customer support.

I recommend that you contact US customer support, even if you don't live in the US.

They are usually more knowledgeable than other countries support.