Upgrade from 8.0.1 to 8.2.1 and my public shares don't work anymore

On Centos 7, running php 5.6 and apache 2.4. I updated using yum update pydio. Other features seem to work okay, but old and new shares return an error. The Event Details in the log are:
Level: Error
Action: error I.311
Params: PluginsService.php
More Info: message=error while loading workspace [Filename.ext]: Error while mounting file system!

If I disable Booster I get another error first before the error above, that error is:
Action: Meta Plugin
Params: Pydio\Code\PluginFramework\PluginsService
More Info: Cannot instanciate Meta plugin, reason: Error while mounting file system!

My share base is /shares, not /public and the filesystems are samba mounts.

Thanks for any help

can you update php to version 7 or above ?