OPC-UA client - Subscription ok in Ignition but not present in OPC-UA server

I have a strange problem with Ignition’s OPC-UA client. Some tags stop updating after working for some days. In the diagnostics i can see that Ignition thinks it has a subscription, but that subscription ist not present in the server. It looks like after an error, Igntion doesn’t renew the subscription.

Ignition version 8.1.5 on Linux
OPC-UA server: TANI PLC-Engine 2.0.2

At the same time the tag stopped updating, there is a log entry:

INFO   | jvm 2    | 2021/06/18 09:20:57 | W [o.e.m.o.s.c.s.OpcUaSubscriptionManager] [07:20:57]: no item for clientHandle=290 
INFO   | jvm 2    | 2021/06/18 09:20:57 | W [o.e.m.o.s.c.s.OpcUaSubscriptionManager] [07:20:57]: no item for clientHandle=289 
INFO   | jvm 2    | 2021/06/18 09:20:57 | W [o.e.m.o.s.c.s.OpcUaSubscriptionManager] [07:20:57]: no item for clientHandle=288 
INFO   | jvm 2    | 2021/06/18 09:21:36 | W [o.e.m.o.s.c.s.OpcUaSubscriptionManager] [07:21:36]: no item for clientHandle=289 

image

The tag is still displayed as subscribed in Ignitions’s client.

But there is no subscription in the server (The active subscription in the screenshot is another Ignition server)
image

Those warnings generally mean a data change notification was received for an item id we don’t have on record any more. It can happen as a timing quirk when a lease change or items are removed and I’m not sure it’s related to the whole subscription being gone.

Leaving org.eclipse.milo.opcua.sdk.client.subscriptions.OpcUaSubscriptionManager on DEBUG might help, along with com.inductiveautomation.ignition.gateway.opcua.client.connection.OpcUaConnection. If the subscription times out or “disappears” some how the server should notify the client with a status change notification for that subscription, which should result in the subscription being removed / resynchronized in the client bookkeeping.