When you run a zwave repair, The hub goes through its device table and attempts to contact each device and ask them who their current neighbors are.
The hub then takes all of this information together and calculate some optimal routes in advance. It sends this routing information back to each individual device, just The part that applies to that specific device. So each device ends up with a partial routing table. All of this should make routing faster and more efficient.
So in a sense the hub asks a question, the node answers, and then the hub sends out a New map for the node to use.
The two common error messages that you will see are
“Failed to update mesh information.” This means the node didn’t answer the first question. It didn’t send back the list of its neighbors. That might mean in the node is missing altogether, it might mean it was just asleep, it might just mean it’s out of range, or it might mean the data was corrupted. If it was just asleep, it’s no big deal. If it’s out of range it may not be a problem as the rest of the map is filled in.
Note in particular that “failed to update mesh information” won’t cause a problem for the network if that particular device was a battery powered device because they don’t act as repeaters. But if that device is a repeater, it can’t be used in routing until the error message goes away, so you can lose access to a lot of other devices down the line.
“Failed to update route”
After the hub has collected all of the information from all of the devices it starts calculating the routes. when it has the partial map ready for a particular device, it sends the information to that device. It should get back an acknowledgement. If it doesn’t, you get the “failed to update route” message.
Again, this can happen for a couple of different reasons. If the device is battery-operated, it might just have gone to sleep again. It happens. if any devices get physically powered off during the repair, it can happen. if devices get moved around it can definitely happen.
When this does happen, it’s actually not that big a deal. It just means that there’s a device out there that doesn’t have the most optimal route.
I’ve mentioned before that a lot of field techs will do 3 zwave repairs in a row. Cleaning up These kinds of errors are the main reason.
Of course you could also get either of these errors because of either data corruption in the address tables or device failure in the hub itself, obviously both a problem. But most the time it’s just a sleepy device that’s thrown something off and it will run fine the next time.
Ghost devices
The ghost device error where you only see a device number not a name and you get “[ ] not responding” is a different kind of error, and one you really shouldn’t see very often. The problem has been well described in posts above, it means the hub has a listing for a device which is no longer on the network. You have to clean up the address table so that the network will stop trying to use it.