trenccan

Thank you. WP_DEBUG_LOG helped me. I was a typo in ic-dph variable so it was undefined.

It looks like the problem is causing $new_data array. But I cant find out more because I dont know how to var_dump the data from the original $form_data array. As I said before everything works fine but the successful message disapeared. If I remove the part with $new_data, the successful CF7 message on submit is working again.

Thank you

add_filter( 'cfdb7_before_save_data', function ( array $form_data ): array {

	$ucastnici = $new_data = array();

	unset($form_data['checkbox-osobne-udaje']);
    unset($form_data['checkbox-spracovanie-udajov']);
    unset($form_data['checkbox-obchodne-podmienky']);
    unset($form_data['checkbox-ucastnik-rovnaky']);
    unset($form_data['checkbox-zdravotnicky-pracovnik']);
 
	$meno = isset($form_data['meno']) ? $form_data['meno'] : 'N/A';
	$email = isset($form_data['email']) ? $form_data['email'] : 'N/A';
	$telefon = isset($form_data['telefon']) ? $form_data['telefon'] : 'N/A';
	$obchodne_meno = isset($form_data['obchodne-meno']) ? $form_data['obchodne-meno'] : 'N/A';
	$obchodne_sidlo = isset($form_data['obchodne-sidlo']) ? $form_data['obchodne-sidlo'] : 'N/A';
	$ico = isset($form_data['ico']) ? $form_data['ico'] : 'N/A';
	$dic = isset($form_data['dic']) ? $form_data['dic'] : 'N/A';
	$id_dph = isset($form_data['id-dph']) ? $form_data['id-dph'] : 'N/A';
	$pocet_registrovanych = isset($form_data['_wpcf7_groups_count']) ? $form_data['_wpcf7_groups_count'] : 'N/A';
	$konferencia = isset($form_data['konferencia']) ? $form_data['konferencia'] : 'N/A';
   
    foreach ($form_data as $key => $value) {

    	for ($i=1; $i < 4 ; $i++) { 
    		$meno_ucastnika 	= "meno-ucastnika__".$i;
    		$email_ucastnika 	= "email-ucastnika__".$i;
    		$meno_komory 		= "meno-komory__".$i;
    		$registracne_cislo 	= "registracne-cislo__".$i;
    		$checkbox = "checkbox-zdravotnicky-pracovnik__".$i;
    		
    		unset($form_data[$checkbox]);

    		$ucastnici[$meno_ucastnika] = isset($form_data[$meno_ucastnika]) ? $form_data[$meno_ucastnika] : 'N/A';
    		
    		$ucastnici[$email_ucastnika] = isset($form_data[$email_ucastnika]) ? $form_data[$email_ucastnika] : 'N/A';
    	
    		$ucastnici[$meno_komory] = isset($form_data[$meno_komory]) ? $form_data[$meno_komory] : 'N/A';
    	
    		$ucastnici[$registracne_cislo] = isset($form_data[$registracne_cislo]) ? $form_data[$registracne_cislo] : 'N/A';
    	}

    /*remove current fields*/
	unset($form_data['meno']);
	unset($form_data['email']);
	unset($form_data['telefon']);
	unset($form_data['obchodne-meno']);
	unset($form_data['obchodne-sidlo']);
	unset($form_data['ico']);
	unset($form_data['dic']);
	unset($form_data['ic-dph']);
	unset($form_data['_wpcf7_groups_count']);

	/*set new fields*/
	$new_data['meno'] = $meno;
	$new_data['email'] = $email;
	$new_data['telefon'] = $telefon;
	$new_data['obchodne-meno'] = $obchodne_meno;
	$new_data['obchodne-sidlo'] = $obchodne_sidlo;
	$new_data['ico'] = $ico;
	$new_data['dic'] = $dic;
	$new_data['ic-dph'] = $ic_dph;
	$new_data['pocet-registrovanych'] = $pocet_registrovanych;
	$new_data['konferencia'] = $konferencia;
  

    }
 
   
     $form_data = array_merge($new_data, $ucastnici);
    
  
    return $form_data;
} );

I prefer the first way. Less database requirements equals better load time and better load time equals better seo ??