The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/10/static/pgupgrade.html
Description:
The postgresql service (since 9.x?) runs under Windows with the integrated
NetworkService account and not with a dedicated postgres account anymore (at
least by using the EnterpriseDB installer).
You can't start a shell as NetworkService (which seems not to be necessary).
But the owner and permissions of the data directory should be checked and
changed afterwards if necessary.
Another problem (not directly of pg_upgrade) is, that pg_upgrade internally
uses xcopy.exe to copy the pg_clog/pg_xact directory. Now, if somebody
redirects the standard output of pg_upgrade.exe but NOT the standard input,
xcopy failes silently and the pg_xact directory (or files within) are
missing.
This is a problem of xcopy.exe, apparently fixed on newer versions of
Windows but existent under Windows 7 x64. After many hours of testing and
searching, I finally found the cause of the failure here:
http://social.msdn.microsoft.com/Forums/en-US/netfxbcl/thread/ab3c0cc7-83c2-4a86-9188-40588b7d1a52/
I can confirm, that redirecting also the standard input of pg_upgrade.exe
solves the problem.