# UaExpert cannot connect with Ignition OPC server on same host

**URL:** <https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824>\
**Category:** Ignition\
**Tags:** opcua, ignition83\
**Created:** [August 18, 2026, 7:41pm UTC](https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824 "2026-08-18T19:41:22Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![maknem](https://avatars.discourse-cdn.com/v4/letter/m/dbc845/32.png) [@maknem](https://forum.inductiveautomation.com/u/maknem)\
**Post date:** [August 18, 2026, 7:41pm UTC](https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824/1 "2026-08-18T19:41:22Z")

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I have trial version of Ignition 8.3.8. I am trying to use the OPC Server in UaExpert OPC client on same host. OPC server is set with below settings

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/3/138536acc48e47a428dd070c47cc99f63891dbca.png)

In trusted certificates I see only Ignition OPC UA Server. Quarantined Certificates is blank.

At UaExpert server I have below

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/0/30d65f2b31f5d4378a0e5c369dfdbd2d70155635.png)

I am using default password.

I see below in logs

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/a/e/ae6aa94a7b3d0e89f2134671885367dc9baacc9a.png)

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<div class="post-metadata">

**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:** [August 18, 2026, 8:00pm UTC](https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824/2 "2026-08-18T20:00:23Z")

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Use the "Custom Discovery" workflow instead:

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/4/848d84cedbe9ef1e3eae650c38029443e538ad6a.png)

Alternatively, you need to enable the "None" security option in Ignition because UaExpert has a bug where it assumes it's going to be able to do unsecured discovery.

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<div class="post-metadata">

**Author:** ![maknem](https://avatars.discourse-cdn.com/v4/letter/m/dbc845/32.png) [@maknem](https://forum.inductiveautomation.com/u/maknem)\
**Post date:** [August 18, 2026, 8:10pm UTC](https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824/3 "2026-08-18T20:10:27Z")

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I tried to add server using custom discovery

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/d/5d1bbdb513f8859d0aaf0a9c15d62d06cbed4b6b.png)

It gets added, but in the log I see

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/b/f/bfa6d510a6ea47626667c1794ff00244f8bcaa91.png)

When I see the connection properties I see below

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/8/a/8a5e59fa15a152ff1849abcd50efa53ca7e2ec43.png)

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<div class="post-metadata">

**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:** [August 18, 2026, 8:15pm UTC](https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824/4 "2026-08-18T20:15:31Z")

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Have you accepted/trusted the UaExpert certificate in Ignition?

Did you recently add the "Sign" option but not yet restart the Ignition Gateway?

What's in the Ignition logs?

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<div class="post-metadata">

**Author:** ![maknem](https://avatars.discourse-cdn.com/v4/letter/m/dbc845/32.png) [@maknem](https://forum.inductiveautomation.com/u/maknem)\
**Post date:** [August 18, 2026, 8:20pm UTC](https://forum.inductiveautomation.com/t/uaexpert-cannot-connect-with-ignition-opc-server-on-same-host/116824/5 "2026-08-18T20:20:29Z")

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I changed security policies to None and Security Mode to Sign

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/e/c/ec7a148fdb676562d255797d4d0a20d82d158bda.png)

Restarted ignition service.

Tried to add server by custom discovery again, the server got added with below settings

 ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/8/38c4a890d486f4185c8a5ab9b1b94ab483def314.png)

I can browse tags now.

not sure why it does not allow w/ security policy as Basic256ha256 & security mode as SignAndEncrypt