# Any idea why my loopback OPC server isn't working? **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [November 20, 2025, 9:48pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335 "2025-11-20T21:48:44Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Leor\_Fishman](https://avatars.discourse-cdn.com/v4/letter/l/e19adc/32.png) [@Leor\_Fishman](https://forum.inductiveautomation.com/u/Leor_Fishman)\ **Post date:** [November 20, 2025, 9:48pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/1 "2025-11-20T21:48:44Z")
Here are all the relevant logs I can pull up: `org.eclipse.milo.opcua.stack.core.UaException: no matching endpoint found: transportProfile=TCP_UASC_UABINARY, endpointUrl=opc.tcp://localhost:62541, securityPolicy=None, securityMode=None` `at org.eclipse.milo.opcua.stack.server.transport.uasc.UascServerAsymmetricHandler.lambda$openSecureChannel$5(UascServerAsymmetricHandler.java:454)` `at java.base/java.util.Optional.orElseThrow(Unknown Source)` `at org.eclipse.milo.opcua.stack.server.transport.uasc.UascServerAsymmetricHandler.openSecureChannel(UascServerAsymmetricHandler.java:444)` `at org.eclipse.milo.opcua.stack.server.transport.uasc.UascServerAsymmetricHandler.lambda$sendOpenSecureChannelResponse$3(UascServerAsymmetricHandler.java:355)` `at org.eclipse.milo.opcua.stack.core.channel.SerializationQueue.lambda$encode$0(SerializationQueue.java:59)` `at org.eclipse.milo.opcua.stack.core.util.TaskQueue$TaskWrapper.run(TaskQueue.java:273)` `at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)` `at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)` LMK if there’s anything to look for in kindling or in the program files. I haven’t upgraded recently, but i’ve been restoring to and from gateway backups pretty regularly. That security token failure is repeated a bunch. ---
**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:** [November 20, 2025, 9:50pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/2 "2025-11-20T21:50:59Z")
Your connection is configured for no security; maybe the server is configured only to allow secure connections (the default configuration). ---
**Author:** ![Leor\_Fishman](https://avatars.discourse-cdn.com/v4/letter/l/e19adc/32.png) [@Leor\_Fishman](https://forum.inductiveautomation.com/u/Leor_Fishman)\ **Post date:** [November 20, 2025, 9:51pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/3 "2025-11-20T21:51:43Z")
![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/0/6/06ecad7a0accd19e5f86cd8cf5afbb0e8948f480.png) which of these values should I be updating? (alternatively what do I change in the ignition opc server loopback config) ---
**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:** [November 20, 2025, 10:14pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/4 "2025-11-20T22:14:28Z")
Run through the endpoint discovery again on the connection and there will only be one endpoint to select. ---
**Author:** ![Leor\_Fishman](https://avatars.discourse-cdn.com/v4/letter/l/e19adc/32.png) [@Leor\_Fishman](https://forum.inductiveautomation.com/u/Leor_Fishman)\ **Post date:** [November 20, 2025, 10:16pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/5 "2025-11-20T22:16:16Z")
Did that, left every value default, and it faulted. ---
**Author:** ![Leor\_Fishman](https://avatars.discourse-cdn.com/v4/letter/l/e19adc/32.png) [@Leor\_Fishman](https://forum.inductiveautomation.com/u/Leor_Fishman)\ **Post date:** [November 20, 2025, 10:20pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/6 "2025-11-20T22:20:04Z")
Now seeing UaServiceFaultException: status=Bad\_UserAccessDenied, message=User does not have permission to perform the requested operation. at org.eclipse.milo.opcua.stack.client.UaStackClient.lambda$deliverResponse$5(UaStackClient.java:337) at org.eclipse.milo.opcua.stack.core.util.ExecutionQueue$Task.run(ExecutionQueue.java:119) 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) 8.1.48 (b2025042910) Azul Systems, Inc. 17.0.14 ---
**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:** [November 20, 2025, 10:20pm UTC](https://forum.inductiveautomation.com/t/any-idea-why-my-loopback-opc-server-isnt-working/112335/7 "2025-11-20T22:20:33Z")
Configure the username and password on the connection to be `opcuauser` / `password`