# Crashing Node Red - OPC UA Client Error

**URL:** <https://discourse.nodered.org/t/crashing-node-red-opc-ua-client-error/73820>\
**Category:** General\
**Created:** [17 January 2023 15:28 UTC](https://discourse.nodered.org/t/crashing-node-red-opc-ua-client-error/73820 "2023-01-17T15:28:35Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![matteovi](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/matteovi/32/64536_2.png) [@matteovi](https://discourse.nodered.org/u/matteovi)\
**Post date:** [17 January 2023 15:28 UTC](https://discourse.nodered.org/t/crashing-node-red-opc-ua-client-error/73820/1 "2023-01-17T15:28:35Z")

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Hi, I have an error with opc ua conncection. My Node-Red crash with this Error "Cannot read properties of undefined (readinf 'callback'). I'll attach a screen of the problem.

 ![errore bieeme](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/b/8/b8dd8474288aed5061bdc30c45af1889f37f2be1.png)

How Can i Fix that?

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**Author:** ![mikakaraila](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/mikakaraila/32/37496_2.png) [@mikakaraila](https://discourse.nodered.org/u/mikakaraila)\
**Post date:** [28 February 2023 16:52 UTC](https://discourse.nodered.org/t/crashing-node-red-opc-ua-client-error/73820/2 "2023-02-28T16:52:44Z")

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Looks like error is related to http request and xml.  
Are you "mixing" msg content with different protocols?

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [29 April 2023 16:53 UTC](https://discourse.nodered.org/t/crashing-node-red-opc-ua-client-error/73820/3 "2023-04-29T16:53:34Z")

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