Question

I’m transferring files using http post request from one host to another.
Receiving host runs apache with php onboard.
The request contains multipart/form-data and is performing by php script (cURL).
There are 86 files with total size about 20Mb.
The issue is the receiving php script gots empty $_POST array.
I reconfigured sending script so it sends the same request in loop but removes one file from data collection on each iteration. When 36 files (total size ~12Mb) are removed the receiving script accepts the data, $_POST variable is populated well.
What can be wrong?
I’ve reviewed all resposible php.ini parameters, so they contain reasonable values.

  ini_set("post_max_size","510M"); 
  ini_set("memory_limit","400M"); 
  ini_set("upload_max_filesize","510M"); 
  ini_set("max_file_uploads","500"); 

Is there a way to investigate the reason? I mean, error_log doesn’t contain anything useful. Maybe there is another source to see?

Answer 1

The post_max_size value cannot be set at runtime on a per-directory basis. Even though your phpinfo() will reflect the change, it will be ignored when a form is processed and will therefore revert back to the default of 8MB.

This is proved by the fact that the total size of your files is 20MB, yet when you remove ~12MB of files, the script works.

20 - 12 = 8MB // Therefore the script works

The only solution for this is to set the value in the php.ini, or alternatively as you are using Apache, you can set the value in an http.conf or .htaccess file.

I too had this issue a while ago, although it was on Windows running IIS. However, the issue is still the same. For more information on the issue please see this thread.

As it turns out, on Windows, you can only set ini directives that are
marked PHP_INI_USER per directory. Unfortunately, upload_max_filesize
and post_max_size are both PHP_INI_PERDIR. From the PHP docs at
http://php.net/manual/en/configuration.changes.php

The settings for the directory would be active for any script running
from this directory or any subdirectory of it. The values under the
key should have the name of the PHP configuration directive and the
string value. PHP constants in the values are not parsed. However,
only configuration values changeable in PHP_INI_USER can be set this
way, PHP_INI_PERDIR values can not.

So even though Plesk has an interface to change those directives, and
even though phpinfo() picks up on them, they do nothing to change the
actual max upload sizes. Plesk should not allow you to change those on
Windows, and phpinfo() should not report the change, but what can you
do.