# OPC UA (KepserverEX) suddenly disconnect and can't reconnect

**URL:** <https://forum.inductiveautomation.com/t/opc-ua-kepserverex-suddenly-disconnect-and-cant-reconnect/99223>\
**Category:** General Discussion\
**Created:** [November 28, 2024, 9:17am UTC](https://forum.inductiveautomation.com/t/opc-ua-kepserverex-suddenly-disconnect-and-cant-reconnect/99223 "2024-11-28T09:17:42Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![hisyam\_agung](https://avatars.discourse-cdn.com/v4/letter/h/9dc877/32.png) [@hisyam\_agung](https://forum.inductiveautomation.com/u/hisyam_agung)\
**Post date:** [November 28, 2024, 9:17am UTC](https://forum.inductiveautomation.com/t/opc-ua-kepserverex-suddenly-disconnect-and-cant-reconnect/99223/1 "2024-11-28T09:17:42Z")

</div>

My KepserverEX suddenly disconnects and shows “Connection attempt to runtime failed” in the event log. Then it timed out and gave me a dialog box asking if I wanted to work offline.  
After that I tried to restart the KepserverEX server and it eventually recovered. I tried tracing to the Threads Log and it displayed the following message before finally OPC could not connect:

 ![KepserverEx](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/6/36fda51eed0f27a86a2decc739b67ed944325804.jpeg)

Does anyone know the cause of this issue and how to resolve it?