On yesterday's monster update, I received the following warning:

$ grep -A1 "/var/cache/man" /var/log/pacman.log

[2016-01-10 00:38] [ALPM] warning: directory permissions differ on /var/cache/man/
filesystem: 2755 package: 755

[2016-07-16 20:55] [ALPM] warning: directory permissions differ on /var/cache/man/
filesystem: 2755 package: 755

... a permission issue on "/var/cache/man/". I unfortunately missed this warning in January, but this time I googled a bit and found this bug report in combination with that one.

It seems to be very similar on my machine:

$ ls -ld /var/cache/man
drwxr-sr-x 39 root root 4096 17.07.2016 00:04 /var/cache/man/

$ cat /usr/lib/tmpfiles.d/man-db.conf
d /var/cache/man 2755 root root 1w

$ ls -l /usr/lib/tmpfiles.d/man-db.conf
-rw-r--r-- 1 root root 35 06.11.2015 20:29 /usr/lib/tmpfiles.d/man-db.conf

$ grep " man-" /var/log/pacman.log
[2015-11-04 15:55] [ALPM] upgraded man-db (2.7.1-1 -> 2.7.4-1)
[2015-11-17 22:05] [ALPM] upgraded man-db (2.7.4-1 -> 2.7.5-1)
[2015-12-12 19:08] [ALPM] upgraded man-pages (4.02-1 -> 4.03-1)
[2016-01-04 19:44] [ALPM] upgraded man-pages (4.03-1 -> 4.04-1)
[2016-03-21 01:01] [ALPM] upgraded man-pages (4.04-1 -> 4.05-1)
[2016-05-16 01:00] [ALPM] upgraded man-pages (4.05-1 -> 4.06-1)
[2016-07-16 21:15] [ALPM] upgraded man-pages (4.06-1 -> 4.06-2)

$ pacman -Qi man-pages
Name : man-pages
Version : 4.06-2
<...>
Installationsgröße : 5,44 MiB
Packer : Anke Boersma <demm@kaosx.us>
Erstellt am : So 03 Jul 2016 22:52:46 CEST
Installiert am : Sa 16 Jul 2016 21:15:51 CEST
Installationsgrund : Ausdrücklich installiert

$ pacman -Qi man-db
Name : man-db
Version : 2.7.5-1
<...>
Installationsgröße : 1400,00 KiB
Packer : Anke Boersma <demm@kaosx.us>
Erstellt am : Fr 06 Nov 2015 20:29:11 CET
Installiert am : Di 17 Nov 2015 22:05:39 CET
Installationsgrund : Ausdrücklich installiert

Any input would be appreciated.

This is a long standing issue, see:
https://github.com/KaOSx/main/commit/4ebefa3cdf64dccc7c2e82f3eaba6a5f954adfd6
adjusted:
https://github.com/KaOSx/main/commit/3c2be9ac2c4df8a2edefdeffd1fc25446f59c827
See the bug report linked in the above commits about questions how to setup /var/cache/man
The package filesystem install the directory with 755, man-db installs files into that directory with 2755.
I could try and see if removing this directory creation in filesystem will let man-db create the needed directory.

    demm Thank you for the links - especially the linked bug report - and your explanation.

    So, if I get you right, you will try to fix it and I am/we are not supposed to fool around manually with permissions and GID?

    Best regards,

    subritix