openerp - Odoo 8 error when trying to open customer -

i using odoo 8 on ubuntu. have problem opening customers (some ok). when try open editing odoo server error...indexerror: list index out of range.

any idea cause problem ? tried search similar problems have not found solution. when want edit client have create new one, tried merge them after creating new 1 error reappears again.

thank , here complete traceback:

odoo server error traceback (most recent call last):   file "/opt/odoo/odoo/openerp/http.py", line 530, in _handle_exception     return super(jsonrequest, self)._handle_exception(exception)   file "/opt/odoo/odoo/openerp/http.py", line 567, in dispatch     result = self._call_function(**self.params)   file "/opt/odoo/odoo/openerp/http.py", line 303, in _call_function     return checked_call(self.db, *args, **kwargs)   file "/opt/odoo/odoo/openerp/service/model.py", line 113, in wrapper     return f(dbname, *args, **kwargs)   file "/opt/odoo/odoo/openerp/http.py", line 300, in checked_call     return self.endpoint(*a, **kw)   file "/opt/odoo/odoo/openerp/http.py", line 796, in __call__     return self.method(*args, **kw)   file "/opt/odoo/odoo/openerp/http.py", line 396, in response_wrap     response = f(*args, **kw)   file "/opt/odoo/odoo/addons/web/controllers/main.py", line 949, in call_kw     return self._call_kw(model, method, args, kwargs)   file "/opt/odoo/odoo/addons/web/controllers/main.py", line 932, in _call_kw     records = getattr(request.session.model(model), method)(*args, **kwargs)   file "/opt/odoo/odoo/openerp/http.py", line 900, in proxy     result = meth(cr, request.uid, *args, **kw)   file "/opt/odoo/odoo/openerp/api.py", line 241, in wrapper     return old_api(self, *args, **kwargs)   file "/opt/odoo/odoo/openerp/models.py", line 3109, in read     result = basemodel.read(records, fields, load=load)   file "/opt/odoo/odoo/openerp/api.py", line 239, in wrapper     return new_api(self, *args, **kwargs)   file "/opt/odoo/odoo/openerp/models.py", line 3141, in read     self._read_from_database(stored)   file "/opt/odoo/odoo/openerp/api.py", line 239, in wrapper     return new_api(self, *args, **kwargs)   file "/opt/odoo/odoo/openerp/models.py", line 3305, in _read_from_database     res2 = self._columns[f].get(cr, self._model, ids, f, user, context=context, values=result)   file "/opt/odoo/odoo/openerp/osv/fields.py", line 1361, in     result = self._fnct(obj, cr, uid, ids, name, self._arg, context)   file "/opt/odoo/odoo/addons/account/partner.py", line 246, in _invoice_total     result[partner.id] = sum(inv.user_currency_price_total inv in invoices)   file "/opt/odoo/odoo/addons/account/partner.py", line 246, in <genexpr>     result[partner.id] = sum(inv.user_currency_price_total inv in invoices)   file "/opt/odoo/odoo/openerp/fields.py", line 760, in __get__     self.determine_value(record)   file "/opt/odoo/odoo/openerp/fields.py", line 853, in determine_value     record._prefetch_field(self)   file "/opt/odoo/odoo/openerp/api.py", line 239, in wrapper     return new_api(self, *args, **kwargs)   file "/opt/odoo/odoo/openerp/models.py", line 3196, in _prefetch_field     result = records.read(list(fnames), load='_classic_write')   file "/opt/odoo/odoo/openerp/api.py", line 239, in wrapper     return new_api(self, *args, **kwargs)   file "/opt/odoo/odoo/openerp/models.py", line 3141, in read     self._read_from_database(stored)   file "/opt/odoo/odoo/openerp/api.py", line 239, in wrapper     return new_api(self, *args, **kwargs)   file "/opt/odoo/odoo/openerp/models.py", line 3292, in _read_from_database     res2 = self._columns[fs[0]].get(cr, self._model, ids, fs, user, context=context, values=result)   file "/opt/odoo/odoo/openerp/osv/fields.py", line 1361, in     result = self._fnct(obj, cr, uid, ids, name, self._arg, context)   file "/opt/odoo/odoo/addons/account/report/account_invoice_report.py", line 40, in _compute_amounts_in_user_currency     currency_rate_id = currency_rate_obj.search(cr, uid, [('rate', '=', 1)], limit=1, context=context)[0] indexerror: list index out of range 

in searching of currency_rate_id, search function getting empty list , trying select first element empty list causes error