305: Joomla 2.5 - The PHP temporary directory is not setWritten by Brad Markle
The PHP temporary directory is not set
The PHP temporary directory is the directory that PHP uses to store an uploaded file before Joomla! can access this file. Whilst the directory not being set isn't always a problem, if you are having issues with manifest files not being detected or uploaded files not being detected, setting this in your php.ini file might fix the issue.
Fixing the The "PHP temporary directory is not set" error
To resolve this issue, you'll need to adjust the upload_tmp_dir setting in your php.ini file.
Not every user will have a php.ini file! Depending on how your server is setup, you may or may not have access to adjust your php.ini settings. If you don't have a php.ini file, most settings you can adjust via a .htaccess file as well. It is best to contact your hosting provider for help with updating the upload_tmp_dir setting. If you host you website with InMotion Hosting, you can find more help here with adjusting your php settings.
In our example, we created /administrator/php.ini and put in the following code:
upload_tmp_dir = /home/userna5/tmp
userna5 is our cPanel username, and in the root of our account we have a writable folder named tmp.