Failing to create new page content after upgrade from D6 to D7

Hello
I migrate my website from Drupal 6 to Drupal 7 with all the content types and cck fields. The website works fine, until I want to add new article based on content type migrated from D6.

The message after submit is:

Notice: Undefined property: stdClass::$fid w file_usage_add() (linia 650 z /includes/file.inc).

PDOException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'fid' cannot be null: INSERT INTO {file_usage} (fid, module, type, id, count) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] => [:db_insert_placeholder_1] => file [:db_insert_placeholder_2] => node [:db_insert_placeholder_3] => 291 [:db_insert_placeholder_4] => 1 ) w file_usage_add() (linia 657 z /includes/file.inc).

Thank you for helping :)