internal error when LoginManager set to none

Having set LoginManager = none, I get the following error message:

Foswiki detected an internal error - please check your Foswiki logs and webserver logs for more information. Can't locate object method "login" via package "Foswiki::LoginManager".

Using the TemplateLogin works fine. The error log when LoginManager is set to 'none' shows the following (full path replaced by ...):

 2013-02-25T15:51:32Z warning | Can't locate object method "login" via package "Foswiki::Lo
ginManager" at .../lib/Foswiki/UI.pm line 460.
 at  .../lib/Foswiki/UI.pm line 460
        Foswiki::UI::logon('Foswiki=HASH(0x2a2d890)') called at  .../lib
/Foswiki/UI.pm line 316
        Foswiki::UI::__ANON__() called at /usr/share/perl5/Error.pm line 416
        eval {...} called at /usr/share/perl5/Error.pm line 408
        Error::subs::try('CODE(0x20c66e8)', 'HASH(0x2a2d458)') called at  .../lib/Foswiki/UI.pm line 435
        Foswiki::UI::_execute('Foswiki::Request=HASH(0x2a1b718)', 'CODE(0x2a02e88)', 'logon'
, 1, 'login', 1) called at  .../lib/Foswiki/UI.pm line 274
        Foswiki::UI::handleRequest('Foswiki::Request=HASH(0x2a1b718)') called at  .../lib/Foswiki/Engine/CGI.pm line 41
        Foswiki::Engine::CGI::run('Foswiki::Engine::CGI=HASH(0x2387ed0)') called at  .../bin/login line 24.

Can anyone suggest how I should troubleshoot this? (I am responsible for the Foswiki instance, but not for the server). I couldn't find any reports of a similar error.

-- JamesWhitby - 25 Feb 2013

It turns out that the webserver had been (deliberately, but unhelpfully) set up to redirect requests to the wiki to go to the login script, probably explaining the symptoms above.

-- JamesWhitby - 25 Feb 2013