I was having trouble with the uploads folder for Wordpress.

When I was trying this I had the following configuration

• Wordpress 2.8.4
• IIS7
• Windows 2008 Web Edition
• PHP 5.3

When trying to upload a file I was getting the following error :- Incompatible archive: PCLZIP_ERR_READ_OPEN_FAIL (-2) : Unable to read archive ‘C:\Windows\TEMP\/wordpress-2.8.5.zip’

to fix this I added the following permissions.

• c:\windows temp – add IUSR and give modify permissions
• c:\windows temp – add IIS_IUSRS and give modify permissions

I was then getting an error saying it could download the upgrade but did not have permissions to delete the plugin.

• \wp-content\plugins – grant modify permission for the IUSR account.

After doing this the upgrades of plugins worked fine.