Tom Lane schrieb am 29.09.2016 um 23:10:
> Thomas Kellerer <spam_eater@gmx.net> writes:
>> for some reason pg_upgrade failed on Windows 10 for me, with an error message that one specifc _vm file couldn't be
copied.
>
> Hmm ... a _vm file would go through rewriteVisibilityMap(), which is new
> code for 9.6 and hasn't really gotten that much testing. Its error
> reporting is shamefully bad --- you can't tell which step failed, and
> I wouldn't even put a lot of faith in the errno being meaningful,
> considering that it does close() calls before capturing the errno.
>
> But what gets my attention in this connection is that it doesn't
> seem to be taking the trouble to open the files in binary mode.
> Could that lead to the reported failure? Not sure, but it seems
> like at the least it could result in corrupted VM files.
I did this on two different computers, one with Windows 10 the other with Windows 7.
(only test-databases, so no real issue anyway)
In both cases running a "vacuum full" for the table in question fixed the problem and pg_upgrade finished without
problems.