Could not start the Listserv (Primary Server) service on \\XXXXXX
Error 1067: The process terminated unexpectedly.

Generally, Windows system errors are not helpful in diagnosing LISTSERV problems. You need to look at the LISTSERV console log (typically found in \LISTSERV\LOG, the logs are called LISTSERV-yyyymmdd.LOG where yyyymmdd is the year, month, and day—e.g., 20181126 for 26 Nov 2018) to see what LISTSERV has to say about this problem.

In most cases, this error means that LISTSERV cannot find a valid LAK for the new product version.  Our upgrade instructions are quite clear that you MUST install a LAK with REL= corresponding to the new product version BEFORE upgrading, or the new version of LISTSERV will not start.

For sites with perpetual licensing, even if your product LAK is for the correct version, this error may also be thrown if the maintenance LAK you have installed has an expiration date earlier than the build date of the version to which you are upgrading.

In any case, the Windows error itself is entirely non-specific and is not helpful in diagnosing the problem.  You need to examine the LISTSERV logs to determine the actual reason for the process termination.  Or, try starting LISTSERV interactively in an elevated command prompt with "lsv start" to see what happens.