i got this....

openerp 6.1 nightly build 05082012 ( demo and fresh data same issue) Debian Squeeze
* addons from lp:openobject-addons/6.1
* extra-addons from lp:openobject-addons/extra-trunk 
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Client Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/common/http.py", line 180, in dispatch
    response["result"] = method(controller, self, **self.params)
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/controllers/main.py", line 1047, in call_button
    action = self.call_common(req, model, method, args, domain_id, context_id)
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/controllers/main.py", line 991, in call_common
    return self._call_kw(req, model, method, args, {})
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/controllers/main.py", line 1005, in _call_kw
    return getattr(req.session.model(model), method)(*args, **kwargs)
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/common/openerplib/main.py", line 250, in proxy
    args, kw)
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/common/openerplib/main.py", line 117, in proxy
    result = self.connector.send(self.service_name, method, *args)
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/common/http.py", line 611, in send
    raise fault


Server Traceback (most recent call last):
  File "/usr/lib/pymodules/python2.6/openerp/addons/web/common/http.py", line 592, in send
    result = openerp.netsvc.dispatch_rpc(service_name, method, args)
  File "/usr/lib/pymodules/python2.6/openerp/netsvc.py", line 360, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/usr/lib/pymodules/python2.6/openerp/service/web_services.py", line 586, in dispatch
    res = fn(db, uid, *params)
  File "/usr/lib/pymodules/python2.6/openerp/osv/osv.py", line 167, in execute_kw
    return self.execute(db, uid, obj, method, *args, **kw or {})
  File "/usr/lib/pymodules/python2.6/openerp/osv/osv.py", line 121, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/usr/lib/pymodules/python2.6/openerp/osv/osv.py", line 176, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/usr/lib/pymodules/python2.6/openerp/osv/osv.py", line 164, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/usr/lib/pymodules/python2.6/openerp/addons/base/module/module.py", line 361, in button_immediate_install
    db, pool = pooler.restart_pool(cr.dbname, update_module=True)
  File "/usr/lib/pymodules/python2.6/openerp/pooler.py", line 39, in restart_pool
    registry = RegistryManager.new(db_name, force_demo, status, update_module, True)
  File "/usr/lib/pymodules/python2.6/openerp/modules/registry.py", line 202, in new
    openerp.modules.load_modules(registry.db, force_demo, status, update_module)
  File "/usr/lib/pymodules/python2.6/openerp/modules/loading.py", line 338, in load_modules
    processed = load_marked_modules(cr, graph, states_to_load, force, status, report, loaded_modules)
  File "/usr/lib/pymodules/python2.6/openerp/modules/loading.py", line 253, in load_marked_modules
    loaded, processed = load_module_graph(cr, graph, progressdict, report=report, skip_modules=loaded_modules)
  File "/usr/lib/pymodules/python2.6/openerp/modules/loading.py", line 192, in load_module_graph
    load_update_xml(module_name, idref, mode)
  File "/usr/lib/pymodules/python2.6/openerp/modules/loading.py", line 90, in <lambda>
    load_update_xml = lambda *args: _load_data(cr, *args, kind='update_xml')
  File "/usr/lib/pymodules/python2.6/openerp/modules/loading.py", line 132, in _load_data
    tools.convert_csv_import(cr, module_name, pathname, fp.read(), idref, mode, noupdate)
  File "/usr/lib/pymodules/python2.6/openerp/tools/convert.py", line 970, in convert_csv_import
    result, rows, warning_msg, dummy = pool.get(model).import_data(cr, uid, fields, datas,mode, module, noupdate, filename=fname_partial)
AttributeError: 'NoneType' object has no attribute 'import_data'
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