diff --git a/views/bootstrap/class.Bootstrap.php b/views/bootstrap/class.Bootstrap.php
index d9dc03ebc..f700cd6b5 100644
--- a/views/bootstrap/class.Bootstrap.php
+++ b/views/bootstrap/class.Bootstrap.php
@@ -1943,7 +1943,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $targetfolder) {
-				$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewFolder.php?folderid='.$targetfolder->getId().'">'.htmlspecialchars($targetfolder->getName()).'</a>';
+				if ($targetfolder)
+					$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewFolder.php?folderid='.$targetfolder->getId().'">'.htmlspecialchars($targetfolder->getName()).'</a>';
 			}
 			return implode('<br />', $tmp);
 			break;
@@ -1951,7 +1952,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $targetdoc) {
-				$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewDocument.php?documentid='.$targetdoc->getId().'">'.htmlspecialchars($targetdoc->getName()).'</a>';
+				if ($targetdoc)
+					$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewDocument.php?documentid='.$targetdoc->getId().'">'.htmlspecialchars($targetdoc->getName()).'</a>';
 			}
 			return implode('<br />', $tmp);
 			break;
@@ -1959,7 +1961,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $curuser) {
-				$tmp[] = htmlspecialchars($curuser->getFullname()." (".$curuser->getLogin().")");
+				if ($curuser)
+					$tmp[] = htmlspecialchars($curuser->getFullname()." (".$curuser->getLogin().")");
 			}
 			return implode('<br />', $tmp);
 			break;
@@ -1967,7 +1970,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $curgroup) {
-				$tmp[] = htmlspecialchars($curgroup->getName());
+				if ($curgroup)
+					$tmp[] = htmlspecialchars($curgroup->getName());
 			}
 			return implode('<br />', $tmp);
 			break;
diff --git a/views/bootstrap4/class.Bootstrap4.php b/views/bootstrap4/class.Bootstrap4.php
index 4a9043612..f7c948c9f 100644
--- a/views/bootstrap4/class.Bootstrap4.php
+++ b/views/bootstrap4/class.Bootstrap4.php
@@ -1962,7 +1962,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $targetfolder) {
-				$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewFolder.php?folderid='.$targetfolder->getId().'">'.htmlspecialchars($targetfolder->getName()).'</a>';
+				if ($targetfolder)
+					$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewFolder.php?folderid='.$targetfolder->getId().'">'.htmlspecialchars($targetfolder->getName()).'</a>';
 			}
 			return implode('<br />', $tmp);
 			break;
@@ -1970,7 +1971,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $targetdoc) {
-				$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewDocument.php?documentid='.$targetdoc->getId().'">'.htmlspecialchars($targetdoc->getName()).'</a>';
+				if ($targetdoc)
+					$tmp[] = '<a href="'.$this->params['settings']->_httpRoot.'out/out.ViewDocument.php?documentid='.$targetdoc->getId().'">'.htmlspecialchars($targetdoc->getName()).'</a>';
 			}
 			return implode('<br />', $tmp);
 			break;
@@ -1978,7 +1980,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $curuser) {
-				$tmp[] = htmlspecialchars($curuser->getFullname()." (".$curuser->getLogin().")");
+				if ($curuser)
+					$tmp[] = htmlspecialchars($curuser->getFullname()." (".$curuser->getLogin().")");
 			}
 			return implode('<br />', $tmp);
 			break;
@@ -1986,7 +1989,8 @@ $(document).ready(function() {
 			$attrs = $attribute->getValueAsArray();
 			$tmp = array();
 			foreach($attrs as $curgroup) {
-				$tmp[] = htmlspecialchars($curgroup->getName());
+				if ($curgroup)
+					$tmp[] = htmlspecialchars($curgroup->getName());
 			}
 			return implode('<br />', $tmp);
 			break;