When installing cobbler (in our case 2.6.11, but it might happen with other versions) from source, because they do not offer binary packages anymore, the web showed this error:

[Tue Oct 08 07:41:00.680646 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793] mod_wsgi (pid=8770): Exception occurred processing WSGI script '/usr/local/share/cobbler/web/cobbler.wsgi'.
.....
.....
[Tue Oct 08 07:41:00.687544 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793] ImproperlyConfigured: The SECRET_KEY setting must not be empty.

The solution is simply to add value to the variable SECRET_KEY in file “/usr/local/share/cobbler/web/settings.py” (this file might be in /usr/share/cobbler/web/settings.py)

root@srv:~# grep -n SECRET_KEY /usr/local/share/cobbler/web/settings.py
39:SECRET_KEY = ''

The 39th line put a randomly generated text. You may use openssl to generate the random text like:

root@srv:~# openssl rand -base64 32
NVb09/5TWmCcqfDBLsvyCppza9lJ5Eyb0HWW4HTlSfo=

Edit the cobbler web setting file and put the string there:

root@srv:~# grep SECRET_KEY /usr/local/share/cobbler/web/settings.py
SECRET_KEY = 'NVb09/5TWmCcqfDBLsvyCppza9lJ5Eyb0HWW4HTlSfo='

The whole output error in the apache logs

The error could be seen in Cobbler web installed in Ubuntu 16 when installing cobbler 2.6.11.

[Tue Oct 08 07:41:00.680646 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793] mod_wsgi (pid=8770): Exception occurred processing WSGI script '/usr/local/share/cobbler/web/cobbler.wsgi'.
[Tue Oct 08 07:41:00.680724 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793] Traceback (most recent call last):
[Tue Oct 08 07:41:00.680764 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]   File "/usr/local/share/cobbler/web/cobbler.wsgi", line 27, in application
[Tue Oct 08 07:41:00.681890 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]     return _application(environ, start_response)
[Tue Oct 08 07:41:00.682025 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]   File "/usr/lib/python2.7/dist-packages/django/core/handlers/wsgi.py", line 170, in __call__
[Tue Oct 08 07:41:00.683222 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]     self.load_middleware()
[Tue Oct 08 07:41:00.683380 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]   File "/usr/lib/python2.7/dist-packages/django/core/handlers/base.py", line 49, in load_middleware
[Tue Oct 08 07:41:00.685006 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]     for middleware_path in settings.MIDDLEWARE_CLASSES:
[Tue Oct 08 07:41:00.685168 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]   File "/usr/lib/python2.7/dist-packages/django/conf/__init__.py", line 48, in __getattr__
[Tue Oct 08 07:41:00.686783 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]     self._setup(name)
[Tue Oct 08 07:41:00.687047 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]   File "/usr/lib/python2.7/dist-packages/django/conf/__init__.py", line 44, in _setup
[Tue Oct 08 07:41:00.687111 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]     self._wrapped = Settings(settings_module)
[Tue Oct 08 07:41:00.687133 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]   File "/usr/lib/python2.7/dist-packages/django/conf/__init__.py", line 113, in __init__
[Tue Oct 08 07:41:00.687472 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793]     raise ImproperlyConfigured("The SECRET_KEY setting must not be empty.")
[Tue Oct 08 07:41:00.687544 2019] [wsgi:error] [pid 8770:tid 140654161590016] [remote 192.168.0.250:5793] ImproperlyConfigured: The SECRET_KEY setting must not be empty.