Vcenter appliance host sensor errors

I am running a vcenter 6.0 appliance. Some time in the last week, the vcenter appliance stopped updating the three individual host's sensor data.

If I click on "Reset sensors", this error pops up:

"The "Resetting host sensors..." operation failed for the entity with the following error message.

An error occurred while trying to communicate with the remote service. See the server logs for details."

If I click on "Update sensors", this error pops up:

"The "Updating hardware data..." operation failed for the entity with the following error message.

An error occurred while trying to communicate with the remote service. See the server logs for details."

• I rebooted the appliance
• I rebooted all three hosts
• All three hosts are running esxi 6.0
• I can open the C# client and all the sensor data is updated.

How to fix it??

Thanks!

Arch