I’ve removed php 5.6 and reinstalled php 5.5 instead and it’s now working as before.
When I replaced php 5.6 , apache2filter was removed too (so my php.ini config file is no longer /etc/php5/apache2filter/php.ini but /etc/php5/cli/php.ini), I don’t know if it could be related to the issues I had (file upload and articles truncated when published) but now it works.