# Bad OPC connection

**URL:** <https://forum.inductiveautomation.com/t/bad-opc-connection/67667>\
**Category:** Ignition\
**Created:** [December 15, 2022, 12:30pm UTC](https://forum.inductiveautomation.com/t/bad-opc-connection/67667 "2022-12-15T12:30:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mootez\_bh](https://avatars.discourse-cdn.com/v4/letter/m/8e8cbc/32.png) [@mootez\_bh](https://forum.inductiveautomation.com/u/mootez_bh)\
**Post date:** [December 15, 2022, 12:30pm UTC](https://forum.inductiveautomation.com/t/bad-opc-connection/67667/1 "2022-12-15T12:30:35Z")

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i'm working on a project to connect machines to Ignition through an OPC server. the connecttion was fine but lately it became faulted and displays this error:

![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/2/d/2de61141747c958c57ab562569a87f3919dd36e8.png)

any idea or hint are welcomed

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**Author:** ![Dechen\_Chuteng](https://avatars.discourse-cdn.com/v4/letter/d/9de0a6/32.png) [@Dechen\_Chuteng](https://forum.inductiveautomation.com/u/Dechen_Chuteng)\
**Post date:** [December 19, 2022, 11:46pm UTC](https://forum.inductiveautomation.com/t/bad-opc-connection/67667/2 "2022-12-19T23:46:25Z")

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Hello mootez\_bh,

What type of OPC UA server are you using? Typically, when we see that error message, we like to perform a Wireshark capture to confirm that the issue is coming from the Uri being mismatched.

You could try regenerating the certificates on both the server and client. Then redo the OPC UA connection.

You also have the open a support ticket with us so that a Support Engineer can help you troubleshoot this further. [https://inductiveautomation.com/support/home/](https://inductiveautomation.com/support/home/)

I found some other forums posts that might be helpful where one of our devs discusses this error message in more depth.

> [@Bad certificate OPC UA Server](https://forum.inductiveautomation.com/t/bad-certificate-opc-ua-server/32327/4):
>
> Sorry this screenshot doesn’t help. Can you get a Wireshark recording of Ignition connecting to this server? edit: and actually, can you get the rest of the logs? And navigate to the Status section of the gateway and find this OPC connection and check the fault reason and stack trace? In 7.9 this application URI message should only be a warning and not what is preventing you from connecting.

> [@TopServer OPC UA	Fail Connection](https://forum.inductiveautomation.com/t/topserver-opc-ua-fail-connection/34410):
>
> Hi everyone, I tried connect TopServer V.6.8.797 but show ‘Faulted’. Ignition version 8.0.12. OS Win7 x64. FAULTED status=Bad\_CertificateUriInvalid, description=The URI specified in the ApplicationDescription does not match the URI in the Certificate. UaException: status=Bad\_CertificateUriInvalid, message=The URI specified in the ApplicationDescription does not match the URI in the Certificate. at org.eclipse.milo.opcua.stack.core.util.CertificateValidationUtil.validateApplicationUri(Certif…