Hello Kyle,

I have have the same traceback at my end without magento connect with latest trunk So I am confirming this issue.

Traceback (most recent call last):
  File "/usr/lib/python2.6/threading.py", line 532, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.6/threading.py", line 484, in run
    self.__target(*self.__args, **self.__kwargs)
  File "/home/tiny/workspace/openobject-addons/procurement/wizard/schedulers_all.py", line 49, in _procure_calculation_all
    context=context)
  File "/home/tiny/workspace/openobject-addons/procurement/procurement.py", line 473, in run_scheduler
    self._procure_confirm(cr, uid, use_new_cursor=use_new_cursor, context=context)
  File "/home/tiny/workspace/openobject-addons/procurement/schedulers.py", line 74, in _procure_confirm
    wf_service.trg_validate(uid, 'procurement.order', proc.id, 'button_check', cr)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/wkf_service.py", line 80, in trg_validate
    res2 = instance.validate(cr, id, ident, signal)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/instance.py", line 48, in validate
    workitem.process(cr, witem, ident, signal, force_running, stack=stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 61, in process
    ok = _split_test(cr, workitem, activity['split_mode'], ident, signal, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 174, in _split_test
    _join_test(cr, t[0], t[1], ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 182, in _join_test
    create(cr,[activity], inst_id, ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 41, in create
    process(cr, res, ident, stack=stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 61, in process
    ok = _split_test(cr, workitem, activity['split_mode'], ident, signal, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 174, in _split_test
    _join_test(cr, t[0], t[1], ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 182, in _join_test
    create(cr,[activity], inst_id, ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 41, in create
    process(cr, res, ident, stack=stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 61, in process
    ok = _split_test(cr, workitem, activity['split_mode'], ident, signal, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 174, in _split_test
    _join_test(cr, t[0], t[1], ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 182, in _join_test
    create(cr,[activity], inst_id, ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 41, in create
    process(cr, res, ident, stack=stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 61, in process
    ok = _split_test(cr, workitem, activity['split_mode'], ident, signal, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 174, in _split_test
    _join_test(cr, t[0], t[1], ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 182, in _join_test
    create(cr,[activity], inst_id, ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 41, in create
    process(cr, res, ident, stack=stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 53, in process
    result = _execute(cr, workitem, activity, ident, stack)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/workitem.py", line 126, in _execute
    id_new = wkf_expr.execute(cr, ident, workitem, activity)
  File "/home/tiny/workspace/openobject-server/openerp/workflow/wkf_expr.py", line 68, in execute
    return _eval_expr(cr, ident, workitem, activity['action'])
  File "/home/tiny/workspace/openobject-server/openerp/workflow/wkf_expr.py", line 58, in _eval_expr
    ret = eval(line, env, nocopy=True)
  File "/home/tiny/workspace/openobject-server/openerp/tools/safe_eval.py", line 284, in safe_eval
    return eval(test_expr(expr,_SAFE_OPCODES, mode=mode), globals_dict, locals_dict)
  File "", line 1, in <module>
  File "/home/tiny/workspace/openobject-server/openerp/osv/orm.py", line 214, in <lambda>
    return lambda *args, **argv: attr(self._cr, self._uid, [self._id], *args, **argv)
  File "/home/tiny/workspace/openobject-addons/mrp/procurement.py", line 66, in action_produce_assign_product
    res = procurement_obj.make_mo(cr, uid, ids, context=context)
  File "/home/tiny/workspace/openobject-addons/mrp/procurement.py", line 101, in make_mo
    [produce_id], properties=[x.id for x in procurement.property_ids])
  File "/home/tiny/workspace/openobject-addons/mrp/mrp.py", line 616, in action_compute
    factor = uom_obj._compute_qty(cr, uid, production.product_uom.id, production.product_qty, bom_point.product_uom.id)
  File "/home/tiny/workspace/openobject-addons/product/product.py", line 136, in _compute_qty
    return self._compute_qty_obj(cr, uid, from_unit, qty, to_unit)
  File "/home/tiny/workspace/openobject-addons/product/product.py", line 143, in _compute_qty_obj
    raise osv.except_osv(_('Error !'), _('Conversion from Product UoM %s to Default UoM %s is not possible as they both belong to different Category!.') % (from_unit.name,to_unit.name,))
except_osv: ('warning', 'Error !')

Thanks.