I tried to reply to similar posts, but couldn't figure out how to do it. So posting again:

Galaxy giving this error when editing workflow, just after creating workflow from existing history:

URL: http://localhost/galaxy/workflow/load_workflow?id=df7a1f0c02a5b08e&_=1352817462148
Module weberror.evalexception.middleware:364 in respond
>>  app_iter = self.application(environ, detect_start_response)
Module paste.debug.prints:98 in __call__
>>  environ, self.app)
Module paste.wsgilib:539 in intercept_output
>>  app_iter = application(environ, replacement_start_response)
Module paste.recursive:80 in __call__
>>  return self.application(environ, start_response)
Module paste.httpexceptions:632 in __call__
>>  return self.application(environ, start_response)
Module galaxy.web.framework.base:160 in __call__
>>  body = method( trans, **kwargs )
Module galaxy.web.framework:73 in decorator
>>  return simplejson.dumps( func( self, trans, *args, **kwargs ) )
Module galaxy.webapps.galaxy.controllers.workflow:733 in load_workflow
>>  'tooltip': module.get_tooltip( static_path=url_for( '/static' ) ),
Module galaxy.workflow.modules:258 in get_tooltip
>>  return self.tool.help.render( static_path=static_path )
AttributeError: 'NoneType' object has no attribute 'render'

Could anyone help me to solve this problem?

Thanks,
Sanjar.