This issue is not limited to a single version of KEPServerEX. According to official PTC support documentation, the problem has been observed across a wide range of versions on several Windows platforms.
Here are the most effective solutions, ordered from simplest to most advanced. 1. Update Windows Root Certificates (Recommended)
| Cause | Explanation | |-------|-------------| | | A fresh installation of Windows (especially older builds like 2012 R2, 2016, or LTSC editions) lacks recent root certificate updates. | | Internet Restriction (Air-Gapped) | Kepware is often installed on industrial PCs or SCADA servers that are physically isolated from the internet. Automatic root certificate updates fail. | | Group Policy (GPO) | Corporate security policies have disabled automatic root certificate updates or removed untrusted certificates. | | Corrupt Certificate Store | The Windows certificate store is damaged. | | Time/Date Mismatch | The system clock or timezone is drastically incorrect. Certificate validity depends on accurate time. | This issue is not limited to a single version of KEPServerEX
If standard installation fails, users have reported success with these alternative methods: Registry Imports
You can also check the installation logs. Navigate to the bootstrap.log file located in C:\Program Files (x86)\Kepware\KEPServerEX\ or C:\Program Files (x86)\PTC\ThingWorxindustrialConnectivity\ . If the issue is resolved, the new log entries will no longer show the tell-tale error codes like -2146893807 (which indicates CERT_E_UNTRUSTEDROOT ), 0x65B , or entries like GlobalSign Failed . Automatic root certificate updates fail
The root certificate issue is almost always caused by a on your local machine.
If your computer is in an air-gapped environment and cannot connect to Windows Update, you can manually update the certificate trust list (CTL). This is the most technical but essential method for offline industrial systems. ordered from simplest to most advanced.
Click , then navigate to the Certification Path tab to identify the Root Certificate at the top of the tree hierarchy.
