Typo in the code

[bonifacyi]

I think you have a typo in the code
/area/settings.php
line 153 quotation marks are missing
fwrite( $configfile, '"retention" => "' . $retention . '",' . "\n" );

[zipurman]

$retention should be an integer not a string, so the quotes should not be there.

[bonifacyi]

without the quotes, an error occurs:
PHP Parse error: syntax error, unexpected ',' in /var/www/html/config.php on line 15
this happens when you first start

[zipurman]

The default value should be 0. If it is then that error will occur. Add quotes wont break anything so if that solves your issue then all good. You could add the following line before line 153 to solve this issue as well.

if (empty($retention)) $retention = 0;