diff --git a/main/inc/lib/course.lib.php b/main/inc/lib/course.lib.php
index e7e6b72cea..d0939cf27c 100644
--- a/main/inc/lib/course.lib.php
+++ b/main/inc/lib/course.lib.php
@@ -1686,12 +1686,15 @@ class CourseManager
 
 		foreach($field_ids as $field_id) {
 			// check if field id is used into table field value
-			if (in_array($field_id,$field_all_ids)) {
-				continue;
-			} else {
-				$sql_course_field = "DELETE FROM $t_cf WHERE id = '$field_id'";
-				api_sql_query($sql_course_field,__FILE__,__LINE__);
+			if (is_array($field_all_ids)) {
+				if (in_array($field_id,$field_all_ids)) {
+					continue;
+				} else {
+					$sql_course_field = "DELETE FROM $t_cf WHERE id = '$field_id'";
+					api_sql_query($sql_course_field,__FILE__,__LINE__);
+				}	
 			}
+			
 		}
 	}
 
diff --git a/main/inc/lib/sessionmanager.lib.php b/main/inc/lib/sessionmanager.lib.php
index b1c04e0139..3884238db5 100644
--- a/main/inc/lib/sessionmanager.lib.php
+++ b/main/inc/lib/sessionmanager.lib.php
@@ -222,12 +222,14 @@ class SessionManager {
 
 		foreach($field_ids as $field_id) {
 			// check if field id is used into table field value
-			if (in_array($field_id,$field_all_ids)) {
-				continue;
-			} else {
-				$sql_session_field = "DELETE FROM $t_sf WHERE id = '$field_id'";
-				api_sql_query($sql_session_field,__FILE__,__LINE__);
-			}
+			if (is_array($field_all_ids)) {
+				if (in_array($field_id,$field_all_ids)) {
+					continue;
+				} else {
+					$sql_session_field = "DELETE FROM $t_sf WHERE id = '$field_id'";
+					api_sql_query($sql_session_field,__FILE__,__LINE__);
+				}	
+			}			
 		}
 	}