Dear community,
Because the Pydio version (the one that is provided by our composer package) is not compatible with PHP >= 7.0.0 and because we lack time for updating that package (too much work to be done since it now requires a database), we decided to disable it for the i-MSCP Serie 1.3.x when PHP >= 7.0.0 is detected (OS PHP version).
In replacement, we provide the MonstaFTP package which is a simple Web FTP client. This package is already available for those that use the 1.3.x branch. See https://packagist.org/packages/imscp/monsta-ftp
Remember that you can change your Web FTP client at any time by running the following command:
Thank you for your understanding.
Note to those which could be unhappy with that decision: You can grab the latest Pydio version and install it yourself 
