The installation wizard may warn you about invalid php.ini directives. You need to manually edit the php.ini file in a text editor to resolve these errors.
Finding the path to php.ini
The installation wizard should show you the path to php.ini. If it does not, you may need to manually locate the file yourself.
Create a new file called "phpinfo.php" with just one line:
<?php phpinfo(); ?>
Upload this to your web server and view it in your browser. (On IIS, you can use the PHP Manager panel to view this information: click Check phpinfo() ).
Near the top you will see a list of files that PHP has used for configuration values:
Most values you will find in the "Loaded Configuration File", but depending on your server setup there may be many different .ini files all containing directives.
Editing php.ini values
Open the php.ini file in a plain-text editor and use the "Find" feature to locate the line instructed. For example, if the installation wizard is instructing you to increase the memory_limit value, just "Find" that string to jump to the location in the file. Remember to save the edited file.
If you cannot find a directive in a file, add a new line to the end of a file instead.
Values that won't change
If you change a value in php.ini, but the value shown by phpinfo() doesn't change, check that the directive doesn't appear more than once in php.ini. If there are multiple versions of the same directive, PHP follows the last one in the file.
This can happen with the upload_tmp_dir directive on IIS/Windows.