SFTP Problem with ros5

Hi,
I have almost all my MK devices in ros4.x, and only one with ros5.rc11.
I can upload files via SFTP in ros4.x, bot I can upload rsc file in MK with ros5.rc11.
In the log the following error message appears:
ssh error expected: 50 got:90

I do not understand the error. Can you give me more information?
My PHP code where I do the sft is:

$filename = 'prueba_test.rsc';
$contect = 'several mikrotik command line instructions';

$methods = array(  'kex' => 'diffie-hellman-group1-sha1',
		  'client_to_server' => array(  'crypt' => '3des-cbc',   'comp' => 'none'),
		  'server_to_client' => array(  'crypt' => 'aes256-cbc,aes192-cbc,aes128-cbc', 'comp' => 'none')
	           );
$connection = ssh2_connect('192.168.1.65,'22, $methods);
ssh2_auth_password($connection, 'my_username', 'my_password');
$sftp = ssh2_sftp($connection);
/*
 * Cremos los descriptores de fichero: uno en el Mikrotik remoto y otro con el servidor de backup
 */
$fd = fopen("ssh2.sftp://$sftp/$filename", 'w');
if (! $fd )
	die("ERROR: Imposible create $filename <br>");
// Write in the file descriptor
$long = fprintf($fd, '%s', $content);
if( $long )
	echo "Backup remoto create successfully: $filename<br>";
fclose( $fd );

can you get this error in some any other way to see more debugging information what your client sends/receives

Also, if you are running latest 5.0rc it would be very interesting to get hands on supout.rif file to see, maybe there is something useful for us as 5.0 has our in-house ssh server in it.