Flow is being developed and tested on multiple platforms and pretty easy to set up. Nevertheless we recommend that you go through the following list before installing Flow, because a server with exotic php.ini settings or wrong file permissions can easily spoil your day.

Server Environment

Not surprisingly, you’ll need a web server for running your Flow-based web application. We recommend Apache (though nginx, IIS and others work too – we just haven’t really tested them). Please make sure that the mod_rewrite module is enabled.


To enable Flow to create symlinks on Windows Server 2008 and higher you need to do some extra configuration. In IIS you need to configure Authentication for your site configuration to use a specific user in the Anonymous Authentication setting. The configured user should also be allowed to create symlinks using the local security policy Local Policies > User Rights Assignments > Create symbolic links

Flow’s persistence mechanism requires a database supported by Doctrine DBAL.


Flow was one of the first PHP projects taking advantage of namespaces and other features introduced in PHP version 5.3. By now we started using features of PHP 7.0, so make sure you have PHP 7.0.0 or later available on your web server. Make sure your PHP CLI binary is the same version!

The default settings and extensions of the PHP distribution should work fine with Flow but it doesn’t hurt checking if the PHP modules mbstring, tokenizer and pdo_mysql are enabled, especially if you compiled PHP yourself.


Make sure the PHP functions exec(), shell_exec(), escapeshellcmd() and escapeshellarg() are not disabled in you PHP installation. They are required for the system to run.

The development context might need more than the default amount of memory. At least during development you should raise the memory limit to about 250 MB in your php.ini file.

In case you get a fatal error message saying something like Maximum function nesting level of '100' reached, aborting!, check your php.ini file for settings regarding Xdebug and modify/add a line xdebug.max_nesting_level = 500 (suggested value).