You deploy a client but the installation fails. The client does not upgrade or install.
For Symantec Endpoint Protection 12.1...run Symantec Diagnostic Tool (SymDiag)
Symantec Diagnostic Tool (SymDiag) is a utility designed to quickly and efficiently diagnose common issues encountered on multiple Symantec products. SymDiag can identify most of the problems that you might run into when installing the client, and provide instructions on how to solve them. If SymDiag cannot identify the problem, it can create a detailed report that you can submit to Technical Support to identify the problem.