# Unknown OPC tags **URL:** \ **Category:** Ignition\ **Created:** [February 27, 2020, 9:04pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679 "2020-02-27T21:04:41Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![pcharles](https://avatars.discourse-cdn.com/v4/letter/p/dbc845/32.png) [@pcharles](https://forum.inductiveautomation.com/u/pcharles)\ **Post date:** [February 27, 2020, 9:04pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/1 "2020-02-27T21:04:41Z")
Tag show up as Unknown on OPC-UA when connected to WinCC Logs show the following: (upload://khujCEHWMtaS0c7Uh18O4QLHNDk.png) ![image](https://us1.discourse-cdn.com/inductiveautomation/original/2X/8/8e25949730c92c07d8a0db6d3156ed4c49d91f62.png) ---
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [February 27, 2020, 9:53pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/2 "2020-02-27T21:53:09Z")
The detailed stacktrace on that ‘Error decoding UaResponseMessage’ may be helpful. ---
**Author:** ![pcharles](https://avatars.discourse-cdn.com/v4/letter/p/dbc845/32.png) [@pcharles](https://forum.inductiveautomation.com/u/pcharles)\ **Post date:** [February 28, 2020, 8:45pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/3 "2020-02-28T20:45:50Z")
```auto java.lang.NegativeArraySizeException: null at java.lang.reflect.Array.newInstance(Unknown Source) at org.eclipse.milo.opcua.stack.core.serialization.OpcUaBinaryStreamDecoder.readArray(OpcUaBinaryStreamDecoder.java:671) at org.eclipse.milo.opcua.stack.core.types.structured.PublishResponse$Codec.decode(PublishResponse.java:118) at org.eclipse.milo.opcua.stack.core.types.structured.PublishResponse$Codec.decode(PublishResponse.java:103) at org.eclipse.milo.opcua.stack.core.serialization.codecs.BuiltinDataTypeCodec.decode(BuiltinDataTypeCodec.java:25) at org.eclipse.milo.opcua.stack.core.serialization.codecs.BuiltinDataTypeCodec.decode(BuiltinDataTypeCodec.java:21) at org.eclipse.milo.opcua.stack.core.serialization.codecs.GenericDataTypeCodec$GenericBinaryDataTypeCodec.decode(GenericDataTypeCodec.java:49) at org.eclipse.milo.opcua.stack.core.serialization.OpcUaBinaryStreamDecoder.readMessage(OpcUaBinaryStreamDecoder.java:774) at org.eclipse.milo.opcua.stack.client.handlers.UaTcpClientMessageHandler$5.onMessageDecoded(UaTcpClientMessageHandler.java:665) at org.eclipse.milo.opcua.stack.core.channel.ChunkDecoder$AbstractDecoder.decode(ChunkDecoder.java:199) at org.eclipse.milo.opcua.stack.core.channel.ChunkDecoder.decode(ChunkDecoder.java:83) at org.eclipse.milo.opcua.stack.core.channel.ChunkDecoder.decodeSymmetric(ChunkDecoder.java:71) at org.eclipse.milo.opcua.stack.client.handlers.UaTcpClientMessageHandler.lambda$onSecureMessage$10(UaTcpClientMessageHandler.java:629) at org.eclipse.milo.opcua.stack.core.channel.SerializationQueue.lambda$decode$1(SerializationQueue.java:64) at org.eclipse.milo.opcua.stack.core.util.ExecutionQueue$PollAndExecute.run(ExecutionQueue.java:107) at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) ``` Here it is: thanks ---
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [February 28, 2020, 8:46pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/4 "2020-02-28T20:46:48Z")
What version of Ignition (and the OPC-UA module) is this? ---
**Author:** ![pcharles](https://avatars.discourse-cdn.com/v4/letter/p/dbc845/32.png) [@pcharles](https://forum.inductiveautomation.com/u/pcharles)\ **Post date:** [February 28, 2020, 8:47pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/5 "2020-02-28T20:47:50Z")
Ignition 7.9.11 and OPC-UA is 4.9.11 ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 28, 2020, 8:56pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/6 "2020-02-28T20:56:24Z")
We might need a Wireshark capture done while this error occurs. Either this server is returning a negative value that isn’t -1 to indicate a null array or something else has gone very wrong in the decoding and the wrong bytes are being decoded. It also wouldn’t hurt to upgrade to 7.9.13 and see if that helps anything. ---
**Author:** ![pcharles](https://avatars.discourse-cdn.com/v4/letter/p/dbc845/32.png) [@pcharles](https://forum.inductiveautomation.com/u/pcharles)\ **Post date:** [February 29, 2020, 2:21pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/7 "2020-02-29T14:21:32Z")
I created a new scan class with OPC Data mode to **Read only** instead of subscription. The tags are finally to good quality! ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [February 29, 2020, 2:44pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/8 "2020-02-29T14:44:13Z")
This is only a workaround for what seems to be a real issue. If you’re interested in getting to the bottom of this go ahead and follow the previous advice about upgrading and possibly a Wireshark capture. ---
**Author:** ![pcharles](https://avatars.discourse-cdn.com/v4/letter/p/dbc845/32.png) [@pcharles](https://forum.inductiveautomation.com/u/pcharles)\ **Post date:** [March 12, 2020, 8:36pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/9 "2020-03-12T20:36:06Z")
I upgraded to 7.9.13 - my OPC connection is now faulted. used: SecurityPolicy: None, MessageSecurity: None: max per node is set to 100 **Previously on 7.9.12 the connection wasn’t faulted with this setting. .** Got - UaException: status=Bad\_NonceInvalid, message=nonce must be at least 32 bytes at org.eclipse.milo.opcua.stack.core.util.NonceUtil.validateNonce(NonceUtil.java:176) at org.eclipse.milo.opcua.stack.core.util.NonceUtil.validateNonce(NonceUtil.java:162) at org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory.activateSession(SessionFsmFactory.java:878) at org.eclipse.milo.opcua.sdk.client.session.SessionFsmFactory.lambda$configureActivatingState$17(SessionFsmFactory.java:345) at com.digitalpetri.strictmachine.dsl.ActionBuilder$PredicatedTransitionAction.execute(ActionBuilder.java:76) at com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate.lambda$run$0(StrictMachine.java:207) at java.util.ArrayList.forEach(Unknown Source) at com.digitalpetri.strictmachine.StrictMachine$PollAndEvaluate.run(StrictMachine.java:198) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) 7.9.13 (b2019120915) Oracle Corporation 1.8.0\_231 her’es a wireshark capture ![capture](https://us1.discourse-cdn.com/inductiveautomation/original/2X/a/a0f68c174eacd86c0a933449e2514bb2e46da321.png) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 12, 2020, 8:54pm UTC](https://forum.inductiveautomation.com/t/unknown-opc-tags/32679/10 "2020-03-12T20:54:16Z")
This is a known issue with some servers described here: [Upgrade 7.9.12 -\> 7.9.13 : Opc Connection faulted](http://forum.inductiveautomation.com/t/upgrade-7-9-12-7-9-13-opc-connection-faulted/30901) If you can switch the connection to use security it should work again, otherwise a downgrade or upgrade to 7.9.14 when it is eventually released will be needed.