For Raspberry PI 3, in order to make sure there is an one to one mapping between apache2 server processes and mod_mono_server4 processes, the /etc/mono_server4/mono-server4-hosts.conf file must contain exactly the following lines:

# Default configuration, don't edit it!
<IfModule mod_mono.c>
  MonoUnixSocket default /tmp/.mod_mono_server4
  MonoServerPath default /usr/bin/mod-mono-server4
  AddType application/x-asp-net .aspx .ashx .asmx .ascx .asax .config .ascx
  MonoApplications /:/home/richard/DevelopmentX64/HVR-Web-App
  MonoPath default /usr/lib/mono/4.5:/usr/lib

Please note that the MonoApplications line is required so that all the mod_mono_server4 process instance have identical argument lists.

However in Ubuntu 16.04 the aforementioned change is not necessary.

What is the reason that Raspberry PI running under Mono 4.4.2 requires the MonoApplications line rather than the MonoApplicationsConfigDir line?

  • You have not cited your sources. If the bulk of the stuff you quote above is simply from someone's blog, they might have written exactly the same thing about Ubuntu -- but they didn't write anything about Ubuntu. I.e., it could be just someone's preferred strategy, and nothing to do with the anything much about the Pi.
    – goldilocks
    Aug 23, 2016 at 12:29
  • @goldilocks, My source is my side-by-side comparison of the /etc/mono_server4/mono-server4-hosts.conf file in Raspberry PI 3 and Ubuntu 16.04.Could the reason that Ubuntu 16.04 ignores the MonoApplicationsConfigDir line in /etc/mono_server4/mono-server4-hosts.conf file be related to the contents of debian.webapp? Thanks.
    – Frank
    Aug 23, 2016 at 12:56
  • I don't use mono so I don't have an answer for you, but if the "in order to make sure [...] file must contain exactly the following lines" are your words (or, are they from comments in that config file? It is not clear...) then it still seems like an assumption, not a fact. Half the config files on the system say "Do not edit!", sometimes it is because they are prone to being overwritten by system updates but most often it is just spurious and really means, "Do not edit unless you know what you are doing".
    – goldilocks
    Aug 23, 2016 at 13:03
  • There are a variety of unusual choices made by the people who package Raspbian, some of which, TBH, seem silly to me (note they do not have anything like the manpower of Debian or Ubuntu). So I don't see any reason to believe this is anything more than just a personal choice made by the packager. But someone who uses mono may come along with a better explanation. It could have to do with other choices made by the packager which do make it necessary.
    – goldilocks
    Aug 23, 2016 at 13:03
  • @goldilocks, Thank you for your comments. I will ask the people who use mono about this topic.Please explain your comment , "It could have to do with other choices made by the packager which do make it necessary."
    – Frank
    Aug 23, 2016 at 13:41

1 Answer 1


Apache2 server gets confused when it sees that the apache2.conf file's , also referred to as httpd.conf file, Mono settings conflict with the mono settings in mono-server4-hosts.conf if debian.webapp is not completely configured. For example, a completey configured debian.webapp looks like this:


So, the argument lists must be identical among all mod-mono-server4 intstances to combat confusion by the apache2 server.

  • @Moderator, I am honored to receive your 10 reputation points from half an hour ago. Thank you,
    – Frank
    Aug 23, 2016 at 15:39

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