diff --git a/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.Firebird.vb b/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.Firebird.vb
index 6cc6f5ee..182e2718 100644
--- a/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.Firebird.vb
+++ b/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.Firebird.vb
@@ -21,15 +21,15 @@ Namespace SyncUsers
             Dim oSyncedUsers As New List(Of ADUser)
 
             Try
-                _logger.Debug("Getting group Id for group {0}", GroupName)
+                _logger.Debug("Getting group Id for group [{0}]", GroupName)
                 oGroupId = GetGroupId(GroupName)
 
                 If oGroupId = 0 Then
-                    _logger.Debug("Group {0} does not exist in database or is not enabled for sync.", GroupName)
+                    _logger.Debug("Group [{0}] does not exist in database or is not enabled for sync.", GroupName)
                     Return oSyncedUsers
                 End If
 
-                _logger.Debug("Using group Id {0}", oGroupId)
+                _logger.Debug("Using group Id [{0}]", oGroupId)
             Catch ex As Exception
                 _logger.Error(ex)
                 Return oSyncedUsers
@@ -41,10 +41,10 @@ Namespace SyncUsers
 
                 ' Check if user already exists
                 Try
-                    _logger.Debug("Checking if user {0} exists", oUser)
+                    _logger.Debug("Checking if user [{0}] exists", oUser)
                     oUserId = GetUserId(oUser.samAccountName)
                     oUserExists = Not IsNothing(oUserId)
-                    _logger.Debug("User {0} exists in database: ", oUser, oUserExists)
+                    _logger.Debug("User [{0}] exists in database: ", oUser, oUserExists)
                 Catch ex As Exception
                     _logger.Error(ex)
                     _logger.Warn("Could not get UserId for user. Skipping")
@@ -54,9 +54,9 @@ Namespace SyncUsers
                 ' I user does not exist, create a new user
                 Try
                     If Not oUserExists Then
-                        _logger.Debug("Creating new user for {0}", oUser)
+                        _logger.Debug("Creating new user for [{0}]", oUser)
                         oUserId = CreateUser(oUser)
-                        _logger.Debug("User created with Id {0}", oUserId)
+                        _logger.Debug("User created with Id [{0}]", oUserId)
                     End If
                 Catch ex As Exception
                     _logger.Error(ex)
@@ -128,7 +128,7 @@ Namespace SyncUsers
         End Function
         Private Function CreateUser(User As ADUser) As Integer Implements ISyncUsers.CreateUser
             Try
-                Dim oSQL = $"SELECT FNICM_RADM_NEW_USER('{User.GivenName}', '{User.Surname}', '{User.samAccountName}', 'AD-Sync') from RDB$DATABASE"
+                Dim oSQL = $"SELECT FNICM_RADM_NEW_USER('{User?.GivenName}', '{User?.Surname}', '{User?.samAccountName}', 'AD-Sync') from RDB$DATABASE"
                 Dim oUserId As Integer = _firebird.GetScalarValue(oSQL)
 
                 Return oUserId
diff --git a/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.MSSQL.vb b/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.MSSQL.vb
index b34ab6c7..ee2ca471 100644
--- a/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.MSSQL.vb
+++ b/Modules.Interfaces/ActiveDirectoryInterface/SyncUsers.MSSQL.vb
@@ -47,10 +47,10 @@ Namespace SyncUsers
 
                 ' Check if user already exists
                 Try
-                    _logger.Debug("Checking if user {0} exists", oUser)
+                    _logger.Debug("Checking if user [{0}] exists", oUser)
                     oUserId = GetUserId(oUser.samAccountName)
                     oUserExists = oUserId > 0
-                    _logger.Debug("User {0} exists in database: {1}", oUser, oUserExists)
+                    _logger.Debug("User [{0}] exists in database: [{1}]", oUser, oUserExists)
                 Catch ex As Exception
                     _logger.Error(ex)
                     _logger.Warn("Could not get UserId for user. Skipping.")
@@ -187,9 +187,15 @@ Namespace SyncUsers
 
         Private Function CreateUser(User As ADUser) As Integer Implements ISyncUsers.CreateUser
             Try
+                If User Is Nothing Then
+                    _logger.Warn("Argument [User] is nothing. Exiting.")
+                    Throw New ArgumentNullException("User")
+                End If
+
                 Dim oUserId As Integer = GetUserId(User.samAccountName)
+
                 If oUserId = 0 Then
-                    Dim oSQL As String = $"INSERT INTO TBDD_USER (PRENAME, NAME, USERNAME, EMAIL, ADDED_WHO) VALUES ('{User.GivenName}', '{User.Surname.Replace("'", "''")}', UPPER('{User.samAccountName.Replace("'", "''")}'), '{User.Email.Replace("'", "''")}', '{ADDED_WHO}')"
+                    Dim oSQL As String = $"INSERT INTO TBDD_USER (PRENAME, NAME, USERNAME, EMAIL, ADDED_WHO) VALUES ('{User?.GivenName}', '{User?.Surname?.Replace("'", "''")}', UPPER('{User?.samAccountName?.Replace("'", "''")}'), '{User?.Email?.Replace("'", "''")}', '{ADDED_WHO}')"
                     Dim oResult = _mssql.ExecuteNonQuery(oSQL)
 
                     If oResult = True Then