How can I fix the error on SOQL?

I wrote this code:

public class ContactSearch {     public static List<Contact> searchForContacts(String lastName, String mailingPostalCode){         List<Contact> contactList= [select ID, Name from Contact where LastName=: lastName and MailingPostalCode=: mailingPostalCode];     return contactList;      }

}

but I keep getting this error: "There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: FIELD_CUSTOM_VALIDATION_EXCEPTION, Mailing Street,City, and Country are required: []. "