Version 5.0.0 beta 4

system/Node/Model.php

@@ -60,6 +60,7 @@ use function in_array;
 use function is_array;
 use function is_int;
 use function is_null;
+use function is_numeric;
 use function strlen;
 use function substr;
 
@@ -3410,7 +3411,12 @@ abstract class Model extends ActiveRecord
 		{
 			$orderColumn = static::$databaseColumnOrder;
 			$order = Db::i()->select( array( "MAX( `" . static::$databasePrefix . static::$databaseColumnOrder . "` )" ), static::$databaseTable, array() )->first();
-			$this->$orderColumn = $order + 1;
+
+			/* Make sure this is numeric; we might be ordering by a string */
+			if( is_numeric( $order ) )
+			{
+				$this->$orderColumn = $order + 1;
+			}
 		}
 
 		if( IPS::classUsesTrait( $this, Icon::class ) and $oldIcon )