Error Code: 1452. Cannot add or update a Child Row: a Foreign key Constraint fails

Question

I’d like to ask a question, or just show me the way.

There is a table called Questionrio from it I take the records in a precedent and organize the data in it.

Here is my code:

CREATE DEFINER=`myroot`@`%` PROCEDURE `SP_OrganizaEnvioPesquisa`()
    BEGIN
        DECLARE no_more_rows BOOLEAN DEFAULT FALSE;
        DECLARE registrantsIds INT DEFAULT 0;

        DECLARE cur CURSOR FOR
        SELECT RegistrantId FROM db_didyoubuy.Questionario GROUP BY RegistrantId;

        DECLARE CONTINUE handler FOR NOT FOUND SET no_more_rows := TRUE;

        OPEN cur;

        questoes : LOOP

        FETCH cur into registrantsIds;
            IF no_more_rows THEN
                leave questoes;
            CLOSE cur;
        END IF;

        INSERT IGNORE INTO db_didyoubuy.Grupo (GrupoId, RegistrantIdReferencia) SELECT UUID(), registrantsIds;
        COMMIT;

        INSERT IGNORE INTO db_didyoubuy.QuestionarioENV (IdQuestionario, NomeDestinatario, EmailDestinatario, TelefoneDestinatario, GrupoId, DataVisita,
        DataEnvio, DataResposta, RegistrantId, HeadingId, HeadingName, CompanyId, CompanyName, TipoVisita, TotalAdPoints, AWSMessageId)  
        SELECT
             Id AS IdQuestionario,
             NomeDestinatario,
             EmailDestinatario,
             TelefoneDestinatario,
             (select GrupoId from db_didyoubuy.Grupo where RegistrantIdReferencia = registrantsIds) as Grupo,
             DataVisita,
             now() AS DataEnvio,
             now() AS DataResposta,      
             RegistrantId,
             HeadingId,
             HeadingName,
             CompanyId,
             CompanyName,
             TipoVisita,
             TotalAdPoints,
             UUID() AS AWSMessageId
         FROM
         db_didyoubuy.Questionario
         WHERE RegistrantId = registrantsIds ORDER BY TotalAdPoints DESC LIMIT 5;  
        COMMIT;

        END LOOP questoes;    

        CLOSE cur;    

    END;

After you run the trial and send a show warnings, return me the following.

I need to insert one for many. In the case of a GUID (UUID) from the Group table for Questionarioenv.

What I do first is a search of all my users (Registrantid) in the table Questionario, and for each of them I insert in the table Group then that same Guid inserted in the table Group I relate to the same user(Registrantid).

The funny thing is that when I Gero the first Inserts in my table Questionarioenv it inserts normal, the second time I need to run the same precedent, it returns me the error.

"Error Code: 1452. Cannot add or update a Child Row: a Foreign key Constraint fails";

My base on sql is pretty basic, I would like a light on how I could fix this precedent or how I could rewrite it.

Thanks in advance.