diff --git a/pandora_console/godmode/alerts/alert_view.php b/pandora_console/godmode/alerts/alert_view.php
index 26dba4cc47..8d4d07e578 100644
--- a/pandora_console/godmode/alerts/alert_view.php
+++ b/pandora_console/godmode/alerts/alert_view.php
@@ -262,7 +262,7 @@ $data[1] = '';
 $table_conditions->data[] = $data;
 
 $data[0] = __('Use special days list');
-$data[1] = (isset($alert['special_day']) && $alert['special_day'] == 1) ? __('Yes') : __('No');
+$data[1] = (isset($template['special_day']) && (int) $template['special_day'] !== 0) ? __('Yes') : __('No');
 $table_conditions->data[] = $data;
 
 $data[0] = __('Time threshold');
diff --git a/pandora_console/include/lib/SpecialDay.php b/pandora_console/include/lib/SpecialDay.php
index 0cd42abdb5..92ab6f04f0 100644
--- a/pandora_console/include/lib/SpecialDay.php
+++ b/pandora_console/include/lib/SpecialDay.php
@@ -78,6 +78,17 @@ class SpecialDay extends Entity
             // Update.
             $updates = $this->fields;
 
+            $exist_special_days = $this->specialDays(
+                [ '`talert_special_days`.*' ],
+                ['date_match' => $updates['date']]
+            );
+
+            if (count($exist_special_days) > 0) {
+                throw new \Exception(
+                    __('Already exist special day in this day.'),
+                );
+            }
+
             $rs = \db_process_sql_update(
                 $this->table,
                 $updates,
@@ -94,6 +105,17 @@ class SpecialDay extends Entity
             // Creation.
             $inserts = $this->fields;
 
+            $exist_special_days = $this->specialDays(
+                [ '`talert_special_days`.*' ],
+                ['date_match' => $inserts['date']]
+            );
+
+            if (count($exist_special_days) > 0) {
+                throw new \Exception(
+                    __('Already exist special day in this day.'),
+                );
+            }
+
             // Clean null fields.
             foreach ($inserts as $k => $v) {
                 if ($v === null) {
diff --git a/pandora_console/views/calendar/special_days.php b/pandora_console/views/calendar/special_days.php
index 26573aa06a..aa0954e51a 100644
--- a/pandora_console/views/calendar/special_days.php
+++ b/pandora_console/views/calendar/special_days.php
@@ -331,7 +331,7 @@ for ($month = 1; $month <= 12; $month++) {
             }
         }
 
-        if ($week == 0 || $week == 6) {
+        if ($week == 0 || $week == 6 || isset($specialDays[$display_year][$display_month][$day]) === true) {
              $cal_table->cellstyle[$cal_line][$week] = 'color: red;';
         }
 
@@ -341,7 +341,7 @@ for ($month = 1; $month <= 12; $month++) {
         $cal_table->cellstyle[$cal_line][$week] .= 'font-size: 18px;';
         $cal_table->data[$cal_line][$week] = $day.'&nbsp;';
 
-        if ($is_management_allowed === true) {
+        if ($is_management_allowed === true && isset($specialDays[$display_year][$display_month][$day]) === false) {
             $cal_table->data[$cal_line][$week] .= '<a href="'.$url.'&op=edit&date='.$date.'" title=';
             $cal_table->data[$cal_line][$week] .= __('Create');
             $cal_table->data[$cal_line][$week] .= '>'.html_print_image(
diff --git a/pandora_console/views/calendar/special_days_edit.php b/pandora_console/views/calendar/special_days_edit.php
index 5bfaa540b4..7ea8c17462 100644
--- a/pandora_console/views/calendar/special_days_edit.php
+++ b/pandora_console/views/calendar/special_days_edit.php
@@ -108,6 +108,7 @@ $inputs[] = [
         'returnAllGroup' => $display_all_group,
         'name'           => 'id_group',
         'selected'       => $specialDay->id_group(),
+        'required'       => true,
     ],
 ];
 
diff --git a/pandora_server/lib/PandoraFMS/Core.pm b/pandora_server/lib/PandoraFMS/Core.pm
index 31774f61c5..460d9dc260 100644
--- a/pandora_server/lib/PandoraFMS/Core.pm
+++ b/pandora_server/lib/PandoraFMS/Core.pm
@@ -535,20 +535,22 @@ sub pandora_evaluate_alert ($$$$$$$;$$$$) {
 	
 	# Get current time
 	my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime(time());
-	
+
+	my @weeks = ( 'none', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday', 'holiday');
+	my $special_day;
+
 	# Check weekday
 	if ($alert->{'special_day'}) {
 		logger ($pa_config, "Checking special days '" . $alert->{'name'} . "'.", 10);
 		my $date = sprintf("%4d%02d%02d", $year + 1900, $mon + 1, $mday);
 		# '0001' means every year.
 		my $date_every_year = sprintf("0001%02d%02d", $mon + 1, $mday);
-		my $special_day = get_db_value ($dbh, 'SELECT day_code FROM talert_special_days WHERE (date = ? OR date = ?) AND (id_group = 0 OR id_group = ?) AND (id_calendar = ?) ORDER BY date DESC', $date, $date_every_year, $alert->{'id_group'}, $alert->{'special_day'});
+		$special_day = get_db_value ($dbh, 'SELECT day_code FROM talert_special_days WHERE (date = ? OR date = ?) AND (id_group = 0 OR id_group = ?) AND (id_calendar = ?) ORDER BY date DESC', $date, $date_every_year, $alert->{'id_group'}, $alert->{'special_day'});
 
 		if (!defined($special_day)) {
 			$special_day = 0;
 		}
 
-		my @weeks = ( 'none', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday', 'sunday', 'holiday');
 		if ($special_day != 0) {
 			logger ($pa_config, $date . " is a special day for " . $alert->{'name'} . ". (as a " . $weeks[$special_day] . ")", 10);
 			return $status if (!defined($alert->{$weeks[$special_day]}) || $alert->{$weeks[$special_day]} == 0);
@@ -565,6 +567,9 @@ sub pandora_evaluate_alert ($$$$$$$;$$$$) {
 	my $schedule;
 	if (defined($alert->{'schedule'}) && $alert->{'schedule'} ne '') {
 		$schedule = PandoraFMS::Tools::p_decode_json($pa_config, $alert->{'schedule'});
+		if ($special_day != 0) {
+			return $status if (!defined($schedule->{$weeks[$special_day]}));
+		}
 	}
 
 	if (defined($schedule)) {
@@ -577,11 +582,18 @@ sub pandora_evaluate_alert ($$$$$$$;$$$$) {
 
 		my $time = sprintf ("%.2d:%.2d:%.2d", $hour, $min, $sec);
 
+		my $schedule_day;
+		if ($special_day != 0 && defined($schedule->{$weeks[$special_day]})) {
+			$schedule_day = $weeks[$special_day];
+		} else {
+			$schedule_day = $DayNames[$wday];
+		}
+
 		#
 		# Check time slots
 		#
 		my $inSlot = 0;
-		foreach my $timeBlock (@{$schedule->{$DayNames[$wday]}}) {
+		foreach my $timeBlock (@{$schedule->{$schedule_day}}) {
 			if ($timeBlock->{'start'} eq $timeBlock->{'end'}) {
 				# All day.
 				$inSlot = 1;