Getting MongoException when calling save method

[Alegznder]

Hi.

I faced a problem when I called save method to save new object.

I used it in model to extend EMongoDocument.
When I called method save in Controller I got MongoException with empty message.
The problem is that before it was working fine, after some changes, this exception started to be thrown every time. I didn't investigate the reason yet.

Before that, I was facing this problem, but it was solved. The reason of appearing was as unknown as it's disappearing.

That's how it looks.
http://awesomescreenshot.com/0ach5tm09

Mongo Version

$ mongod --version
db version v2.0.4, pdfile version 4.5
Tue Sep 25 20:11:54 git version: nogitversion

PHP version

$ php --version
PHP 5.3.10-1ubuntu3.4 with Suhosin-Patch (cli) (built: Sep 12 2012 18:59:41)
Copyright (c) 1997-2012 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2012 Zend Technologies
with Xdebug v2.1.0, Copyright (c) 2002-2010, by Derick Rethans
with Suhosin v0.9.33, Copyright (c) 2007-2012, by SektionEins GmbH