DB Error: constraint violation in Civicrm

Question

SQL query: Copy

INSERT INTO `civicrm_activity_contact` 
            (`activity_id` , `contact_id` , `record_type_id` ) 
    VALUES  ( 21102 ,  0 ,  3 );

MySQL said: Documentation #1452 - Cannot add or update a child row: a foreign key constraint fails (cnb_civi.civicrm_activity_contact, CONSTRAINT FK_civicrm_activity_contact_contact_id FOREIGN KEY (contact_id) REFERENCES civicrm_contact (id) ON DELETE CASCADE ON UPDATE RESTRICT)your text

I am edit my form , and facing this error