| Problem | Likely Cause | Solution |
|---------|--------------|----------|
| “OPC Server not found” | OPC Core Components missing | Install from OPC Foundation |
| Access denied (E_ACCESSDENIED) | DCOM permissions | Run dcomcnfg → give Anonymous/Everyone launch & activation rights |
| Installer hangs | Antivirus blocking | Disable AV temporarily |
| Cannot browse remote server | Firewall blocking DCOM (port 135) | Allow port 135 TCP in Windows Firewall |
| “Class not registered” | 32‑vs‑64-bit mismatch | Use 32‑bit OPC Client for 32‑bit OPC servers |
Before you run the installer, ensure you have the following in place. Attempting to install without these will likely result in "Class not registered" errors or failed COM connections. factorysoft opc client install