Error Code: 1452. Can not add or update child row: a foreign key constraint fails

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

There is a table called Questionnaire from it I get the records in a procedure 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 executing the procedure and sending a show warnings, it returns the following.

Ineedtodoaone-to-manyinsertion.InthiscaseaGUID(UUID)fromtheGrouptablefortheQuestionnaire.

WhatIdofirstisasearchofallmyusers(RegistrantId)intheQuestionnairetable,andforeachofthemIinsertintheGrouptablethenthatsameGuidinsertedintheGrouptableIrelatetothesameuser(RegistrantId).

ThefunnythingisthatwhenIgeneratethefirstinsertsinmyQuestionNeveltableitinsertsnormal,thesecondtimeIneedtorunthesameprocedure,itreturnsmetheerror.

"Error Code: 1452. Can not add or update child row: a foreign key constraint fails";

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

Thank you in advance.