The upgrade path i took was to install a fresh version of 2.4, not an actual upgrade of code - apologies for not making that clear. this evening i have removed and readded all z-wave things - now i have another couple of additional unknown nodes.
Does the zwave binding not recreate the XML files if there is a problem with them? Maybe I should remove the node 23 and delete the XML file? Nodes 23 & 24 are next to each other in the shed at the bottom of the garden and have been for a coupe of years now
The xml files are recreated is something changes. For example during a nightly heal.
If you are talking about excluding and reincluding: no, this is normally not necessary and should be the very last step.
I first would do a soft reset of the controller: shutdown your openHAB server, disconnect power (or remove the controller physically), reconnect power, start openHAB.
Next step would be to reiniaialize the device in question (you need to switch to advanced settings in HABmin). This also recreates the xml files.
If those are battery devices, wake them up manually, this may have to be done several times.