Failed to Obtain a Valid CLSID for Server Error in OPC Quick Client

Updated Apr 14, 2023

Reported In


  • OPC Servers

Issue Details

Even after restart OPC Server Runtime Service disconnect and connect again, when I try to read my tags on OPC Quick Client, I receive the error 'Failed to obtain a valid CLSID for server National Instruments.NIOPCServers.V5' 


Below it has some procedure that may solve that issue.
  1. Check if all necessary services are started on the computers. For that:
  • Go to Start >> Control Panel >> Administrative Tools >> Services.
  • Check whether the NI System Web Server, NI Variable Engine, NI Application Web Server, and OPCEnum services are started.
  • If not, try starting them by right-click on the service and selecting Start. 
  1. If the previous attempt does not resolve the issue, you should check the DCOM settings. DCOM settings are security settings for the technology that OPC is built on. To communicate between different computers using OPC, we need to make sure that the DCOM settings are set to allow remote access and that the firewall is not blocking that communication. 
  • To ensure the DCOM settings are well set and add exception to the Windows Firewall. For that, refer to the OPC Foundation document Using OPC via DCOM with Microsoft XP Service Pack 2. Though the document is for Windows XP Service Pack 2, in the case of newer operating system as Windows 7, 8 or 10, mainly the UI appearance has changed.
  • On the section Configuring DCOM for an individual OPC Server, ensure to modify the DCOM settings for all NI related Component Services (National Instruments Variable Engine, etc) in additional to OPCEnum. 
  1. If none of the previous procedures have solved the issue, try to uninstall and install again the NI OPC Server. Refer to the article Uninstall or Repair National Instruments Software or Drivers in Windows  if needed.