Everyone's Enterprise deployments are unique, which could be basic to complex. Which makes the solutions varied. There are a couple of things that could have occurred, without an Esri Support analyst combing over your deployment and error logs, I can only provide broad suggestions.
Theoretical reasons this could occur:
- The connection between the local machine and ArcGIS for Server is unstable or intermittent. This causes ArcGIS for Server to be unable to establish communication with other machines and returns the error.
- Processing and memory limitations of the server may return the error. The server crashes or becomes unresponsive when overloaded with requests or is unable to process a large amount of data.
- I would check to see the system resources (RAM, Cores, ArcSOCS, disk space)
- If the machines could reach each other
- If the upgrade failed in any section
- If anti-virus is targeting our software
- Your certificates are having issues
I would recommend sending a ticket to support for them to review your environment and the problem you encountered.
Amanda De Medeiros
Esri Canada