Question: I'm running into a strange issue when uploading large files via PHP (through Drupal, though that's not the issue).

Basically, my file uploads fail due to post\_max\_size limits being reached, even though the local directive is set to 96M, and the file is 25M. 

I've ensured everything else is correct, including `max_input_time`, `max_upload_filesize`, and the IIS FastCGI idle time. All these are plenty large and not the issue.

I am overriding the `post_max_size` directive through Plesk, which (I believe) stores the change in a registry value. Running phpinfo() on the domain shows the correct local and master values for all directives...96M local, 12M master.

The very strange thing is that when I change the master `post_max_size` in php.ini from 12M to 96M (and ensure the change has taken effect), **it works normally!** Changing the master value back to 12M (and keeping a local value of 96M) immediately causes uploads to fail again.

Is this a bug in PHP, or am I doing it wrong?

Answer: 
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.
I had similar issues in Plesk. Have you edited any of the templates in Plesk? I know when it runs its cron jobs you can lose certain config edits if you didn't do them via Plesk.

But what about your .htaccess file? You can also set these limits there and that, based on your Plesk config, may the better place to make these changes.