Error importing products - AdminImport::utf8_encode_array() expected to be a reference,

[Higgly]

PrestaShop 1.4.0.17
Php 5.3

After uploading the csv i click on next and i get this error repeated many times:

Warning: Parameter 1 to AdminImport::utf8_encode_array() expected to be a reference, value given in /var/www/vhosts/zz.zzzz.zz/httpdocs/shop/admin/tabs/AdminImport.php on line 408 Warning

I've used this function without problems a few days ago.

Any suggestion?

Thanks!