Error !

ValueError: invalid literal for int() with base 10: 'None'

116
<div>

117
    % if room != False and str(room.strip()) != '':

118
    % if sfilter == 'yes':

119
    <span class="linkbottondark"><a href="/${currentsem}/${il}/${site}/${lang}/?sfilter=no&amp;room=${ax.Rooms(axobj,int(room)).id}">ohne LVs</a></span>

120
    % else:

121
    <span class="linkbottondark"><a href="/${currentsem}/${il}/${site}/${lang}/?sfilter=yes&amp;room=${ax.Rooms(axobj,int(room)).id}">mit LVs</a></span>

122
    % endif

123
    % else:

124
    % if sfilter == 'yes':
/var/www/vlvz.py/vlvz/templates/filter.mako, line 119:
119
    <span class="linkbottondark"><a href="/${currentsem}/${il}/${site}/${lang}/?sfilter=no&amp;room=${ax.Rooms(axobj,int(room)).id}">ohne LVs</a></span>
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 761:
761
callable_(ctx, **kwargs)
/var/www/vlvz.py/vlvz/templates/reservierung.mako, line 204:
204
<%include file="/filter.mako"/>
/var/www/vlvz.py/vlvz/templates/base.mako, line 286:
286
				${self.filter()}
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 899:
899
callable_(context, *args, **kwargs)
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 873:
873
_exec_template(inherit, lclcontext, args=args, kwargs=kwargs)
/usr/lib/python2.7/dist-packages/mako/runtime.py, line 838:
838
**_kwargs_for_callable(callable_, data))
/usr/lib/python2.7/dist-packages/mako/template.py, line 462:
462
return runtime._render(self, self.callable_, args, data)
/var/www/vlvz.py/vlvz/webvlvz2.py, line 334:
334
return tpl.render(**data)