field.attach.inc error on cron run and lot of field_invoke errors

Hi,
I've tried to upgrade drupal 6.x site to drupal 7. So I've uninstalled all non-core modules (I want to build all "from scratch"), etc. Upgrade process finishes succesfully, but I can't run cron jobs and I've got lot of notice messages in watchdog table. Here are these messages, could someone help to find the problem? :) I can put more specific information if necessary.

root@srv:/opt/drush# ./drush cron
PHP Fatal error:  Cannot access empty property in /opt/d6/modules/field/field.attach.inc on line 317
Drush command could not be completed.                                                                                                                                                                                             [error]

{drush wd-list for notice}
 Id  Data          Priorytet  Typ  WiadomoĹ
 17  26/li. 20:12  notice     php  Notice: Undefined index:  in _field_invoke_multiple() (line 300 of /opt/d6/modules/field/field.attach.inc).
 16  26/li. 20:12  notice     php  Notice: Undefined index: field_name in _field_invoke_multiple() (line 299 of /opt/d6/modules/field/field.attach.inc).
 15  26/li. 20:12  notice     php  Notice: Undefined index: field_id in _field_invoke_multiple() (line 298 of /opt/d6/modules/field/field.attach.inc).
 14  26/li. 20:12  notice     php  Notice: Undefined property: stdClass::$type in entity_extract_ids() (line 7240 of /opt/d6/includes/common.inc).
 13  26/li. 20:12  notice     php  Notice: Undefined index:  in _field_invoke_multiple() (line 300 of /opt/d6/modules/field/field.attach.inc).
 12  26/li. 20:12  notice     php  Notice: Undefined index: field_name in _field_invoke_multiple() (line 299 of /opt/d6/modules/field/field.attach.inc).
 11  26/li. 20:12  notice     php  Notice: Undefined index: field_id in _field_invoke_multiple() (line 298 of /opt/d6/modules/field/field.attach.inc).
 10  26/li. 20:12  notice     php  Notice: Undefined index:  in _field_invoke_multiple() (line 300 of /opt/d6/modules/field/field.attach.inc).
 9   26/li. 20:12  notice     php  Notice: Undefined index: field_name in _field_invoke_multiple() (line 299 of /opt/d6/modules/field/field.attach.inc).
 8   26/li. 20:12  notice     php  Notice: Undefined index: field_id in _field_invoke_multiple() (line 298 of /opt/d6/modules/field/field.attach.inc).