diff --git a/htdocs/core/actions_massactions.inc.php b/htdocs/core/actions_massactions.inc.php
index 85725b16547..72279faf16b 100644
--- a/htdocs/core/actions_massactions.inc.php
+++ b/htdocs/core/actions_massactions.inc.php
@@ -593,8 +593,10 @@ if (!$error && $massaction == 'confirm_presend') {
 							if ($mailfile->error) {
 								$resaction .= $langs->trans('ErrorFailedToSendMail', $from, $sendto);
 								$resaction .= '<br><div class="error">'.$mailfile->error.'</div>';
-							} else {
+							} elseif (!empty($conf->global->MAIN_DISABLE_ALL_MAILS)) {
 								$resaction .= '<div class="warning">No mail sent. Feature is disabled by option MAIN_DISABLE_ALL_MAILS</div>';
+							} else {
+								$resaction .= $langs->trans('ErrorFailedToSendMail', $from, $sendto) . '<br><div class="error">(unhandled error)</div>';
 							}
 						}
 					}
diff --git a/htdocs/core/class/CMailFile.class.php b/htdocs/core/class/CMailFile.class.php
index 863bb9a6794..5683c8e6a07 100644
--- a/htdocs/core/class/CMailFile.class.php
+++ b/htdocs/core/class/CMailFile.class.php
@@ -926,7 +926,7 @@ class CMailFile
 				}
 				// send mail
 				try {
-					$result = $this->mailer->send($this->message);
+					$result = $this->mailer->send($this->message, $failedRecipients);
 				} catch (Exception $e) {
 					$this->error = $e->getMessage();
 				}
@@ -936,6 +936,9 @@ class CMailFile
 
 				$res = true;
 				if (!empty($this->error) || !$result) {
+					if (!empty($failedRecipients)) {
+						$this->error = 'Transport failed for the following addresses: "' . join('", "', $failedRecipients) . '".';
+					}
 					dol_syslog("CMailFile::sendfile: mail end error=".$this->error, LOG_ERR);
 					$res = false;
 				} else {
diff --git a/htdocs/product/price.php b/htdocs/product/price.php
index 7dfb94be79f..9548643166a 100644
--- a/htdocs/product/price.php
+++ b/htdocs/product/price.php
@@ -1470,7 +1470,6 @@ if ((empty($conf->global->PRODUIT_CUSTOMER_PRICES) || $action == 'showlog_defaul
 			}
 
 			print '<td class="center">'.$langs->trans("PriceBase").'</td>';
-			print $conf->global->PRODUIT_MULTIPRICES_USE_VAT_PER_LEVEL;
 			if (empty($conf->global->PRODUIT_MULTIPRICES) && empty($conf->global->PRODUIT_CUSTOMER_PRICES_BY_QTY_MULTIPRICES)) {
 				print '<td class="right">'.$langs->trans("DefaultTaxRate").'</td>';
 			}
diff --git a/htdocs/societe/class/societe.class.php b/htdocs/societe/class/societe.class.php
index e53675d8bb6..cb0f91851f2 100644
--- a/htdocs/societe/class/societe.class.php
+++ b/htdocs/societe/class/societe.class.php
@@ -3332,17 +3332,58 @@ class Societe extends CommonObject
 	{
 		// phpcs:enable
 		if ($this->id) {
-			$sql = "UPDATE ".MAIN_DB_PREFIX."societe";
-			$sql .= " SET parent = ".($id > 0 ? $id : "null");
-			$sql .= " WHERE rowid = ".$this->id;
-			dol_syslog(get_class($this).'::set_parent', LOG_DEBUG);
-			$resql = $this->db->query($sql);
-			if ($resql) {
-				$this->parent = $id;
+			// Check if the id we want to add as parent has not already one parent that is the current id we try to update
+			$sameparent	= $this->validateFamilyTree($id, $this->id, 0);
+			if ($sameparent < 0) {
+				return -1;
+			} elseif ($sameparent == 1) {
+				setEventMessages('ParentCompanyToAddIsAlreadyAChildOfModifiedCompany', null, 'warnings');
+				return -1;
+			} else {
+				$sql = 'UPDATE '.MAIN_DB_PREFIX.'societe SET parent = '.($id > 0 ? $id : 'null').' WHERE rowid = '.((int) $this->id);
+				dol_syslog(get_class($this).'::set_parent', LOG_DEBUG);
+				$resql	= $this->db->query($sql);
+				if ($resql) {
+					$this->parent	= $id;
+					return 1;
+				} else {
+					return -1;
+				}
+			}
+		} else {
+			return -1;
+		}
+	}
+
+	/**
+	 *    Check if a thirdparty $idchild is or not inside the parents (or grand parents) of another thirdparty id $idparent.
+	 *
+	 *    @param	int		$idparent	Id of thirdparty to check
+	 *    @param	int		$idchild	Id of thirdparty to compare to
+	 *    @param    int     $counter    Counter to protect against infinite loops
+	 *    @return	int     			<0 if KO, 0 if OK or 1 if at some level a parent company was the child to compare to
+	 */
+    public function validateFamilyTree($idparent, $idchild, $counter = 0)
+	{
+		if ($counter > 100) {
+			dol_syslog("Too high level of parent - child for company. May be an infinite loop ?", LOG_WARNING);
+		}
+		
+		$sql	= 'SELECT s.parent';
+		$sql	.= ' FROM '.MAIN_DB_PREFIX.'societe as s';
+		$sql	.= ' WHERE rowid = '.$idparent;
+		$resql	= $this->db->query($sql);
+		if ($resql) {
+			$obj	= $this->db->fetch_object($resql);
+
+			if ($obj->parent == '')	{
+				return 0;
+			} elseif ($obj->parent == $idchild)	{
 				return 1;
 			} else {
-				return -1;
+				$sameparent	= $this->validateFamilyTree($obj->parent, $idchild, ($counter + 1));
 			}
+			return $sameparent;
 		} else {
 			return -1;
 		}