# GENERAL\_PROTOCOL\_EXCEPTION between two 8.1.27 gateways connected via GAN and RTP

**URL:** <https://forum.inductiveautomation.com/t/general-protocol-exception-between-two-8-1-27-gateways-connected-via-gan-and-rtp/74104>\
**Category:** Ignition\
**Tags:** ignition81\
**Created:** [May 24, 2023, 3:01am UTC](https://forum.inductiveautomation.com/t/general-protocol-exception-between-two-8-1-27-gateways-connected-via-gan-and-rtp/74104 "2023-05-24T03:01:41Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jaydeepcheruku](https://avatars.discourse-cdn.com/v4/letter/j/c77e96/32.png) [@jaydeepcheruku](https://forum.inductiveautomation.com/u/jaydeepcheruku)\
**Post date:** [May 24, 2023, 3:01am UTC](https://forum.inductiveautomation.com/t/general-protocol-exception-between-two-8-1-27-gateways-connected-via-gan-and-rtp/74104/1 "2023-05-24T03:01:41Z")

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Hellow all, we had the same "GENERAL\_PROTOCOL\_EXCEPTION" error couple of months before between our gateways connected via GAN but with ignition support help after numerous trails and calls were able to identify the source to be voice module. Since we don't use that module we uninstalled the module and things started work again.

Now we added another gateway to the GAN and below is the setup.  
**Gateway1:** We have 8.1.27 gateway with a dataset memory tag  
**Gateway2:** We have another 8.1.27 gateway with Outgoing GAN into above gateway and RTP setup.

**Error on Gateway2 status page:**  
com.inductiveautomation.metro.api.ex.RemoteException: Exception occurred on remote machine, message id='18993', error code=GENERAL\_PROTOCOL\_EXCEPTION [100]  
at com.inductiveautomation.metro.impl.protocol.handler.AckErrorHandler.handleMessage(AckErrorHandler.java:76)  
at com.inductiveautomation.metro.impl.protocol.websocket.WebSocketConnection$RunSend.run(WebSocketConnection.java:1879)  
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)  
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)  
at java.base/java.lang.Thread.run(Unknown Source)

**Error on Gateway1 status page:**  
com.inductiveautomation.metro.api.ex.RemoteException: Exception occurred on remote machine, message id='28203', error code=GENERAL\_PROTOCOL\_EXCEPTION [100]  
at com.inductiveautomation.metro.impl.protocol.handler.AckErrorHandler.handleMessage(AckErrorHandler.java:76)  
at com.inductiveautomation.metro.impl.protocol.websocket.MetroWebSocket.onMessage(MetroWebSocket.java:378)  
at org.eclipse.jetty.websocket.core.internal.messages.DispatchedMessageSink.lambda$accept$0(DispatchedMessageSink.java:122)  
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:934)  
at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1078)  
at java.base/java.lang.Thread.run(Unknown Source)

Appreciate the help

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<div class="post-metadata">

**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\
**Post date:** [May 24, 2023, 11:47am UTC](https://forum.inductiveautomation.com/t/general-protocol-exception-between-two-8-1-27-gateways-connected-via-gan-and-rtp/74104/2 "2023-05-24T11:47:00Z")

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Is the dataset memory tag very large? You might be exceeding the GAN's message size limits.

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**Author:** ![jaydeepcheruku](https://avatars.discourse-cdn.com/v4/letter/j/c77e96/32.png) [@jaydeepcheruku](https://forum.inductiveautomation.com/u/jaydeepcheruku)\
**Post date:** [May 24, 2023, 2:55pm UTC](https://forum.inductiveautomation.com/t/general-protocol-exception-between-two-8-1-27-gateways-connected-via-gan-and-rtp/74104/3 "2023-05-24T14:55:19Z")

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Seems like the issue is 8.1 present since 2021 😊

One of our team members was able to find this notes from then support analysis : **“Seems that the problem comes when referencing the tag's own LastChange property. Since technically the tag's LastChange gets updated every time that binding gets evaluated, it leads to an infinite loop and will cause issues with the rest of the project.”** And the issue is resolved now by identifying the tag expression that is using **.LastChange** and fixing that. No more errors and now we are able to save the project with out any issues.