Broken NodeIds after Upgrading KEPServerEX

The Issue

Ignition versions 8.x introduced a change to its OPC Item Path structure that works in a less convenient way for some specific PTC product upgrades. An issue now occurs when upgrading an instance of KEPServerEx to one of two following products:  

• ThingWorx Kepware Server version 6.17
• Kepware Server 7.0.236.0

The following error will appear for tag subscriptions with this scenario:

"Bad_NodeIdUnknown: The node id refers to a node that does not exist in the server address space"

This error is due to the change in Ignition’s the OPC Item Path’s default properties that are now  automatically generated for new tag subscription actions within an OPC Browse. Namespace URI (NSU) is the default property that replaced Namespace Index (ex: ns=2) for 8.x versions. In the event that an existing PTC product experiences an upgrade with a NSU change, all subscribed tags to that server will retain the previous NSU value and need to be changed to retain their subscriptions.

Note: Upgrading existing instances of KEPServerEx to version 7.0.236.0 or higher will result in the product name change to Kepware Server as stated in this PTC knowledgebase article.

The Solution

If you have recently updated your PTC product in the scenario described above and are experiencing a Bad_NodeIdUnknown error for your tags, refer to the following steps:

1. In your Ignition Designer, export your tags to an external file type of your choice (.json, .xml, etc.)
2. Open the tag export file using your preferred text editor.
3. Perform a Find-and-Replace action towards the address area nsu located within the OPCItemPath property of each tag affected by Kepware. This will involve replacing the string value of nsu, KEPServerEx, with the value of either ThingWorx Kepware Server or Kepware Server depending on which PTC was selected for upgrade.

For example, replace:

nsu=KEPServerEx;s=...

with

nsu=Kepware Server;s=...

4. Save changes to a tag export file and import the file back into the Designer. 
5. If new issues appear after import, import the previous tag export file to restart this process.