I was having a problem where uploaded images were causing a 550.50 error when users clicked on them to see the original image. That is, images showed up in articles fine, but when the user tried to view the full size version it errored. I was able to fix the problem by setting the permissions of the temp directory that my php.ini file points to such that they matched what wordpress needed. Here’s the two best sources I found on the subject. After the links I’ll post the contents of the archive.org page including all the info you need.

So here’s an attempt at answering the question that did pretty well. It didn’t work for me exactly (I think they got IUSR and IUSRS backwards), but it’s pretty much right. Either way I found this other page that was referenced on that one even more useful.

Here’s that page quoted in it’s entirety because archive.org can have pages dropped and I’m going to want this info later. It’s original location was at the following url. I’m not linking to it because it’s a dead link, but I will link to the primary page for that site.

http://www.digitalpimple.com/tutorials/windows-tutorials/fix-550-rewrite-error

Begin Quote:

While creating this blog I ran into a rather interesting problem that took me all of a half day to figure out. If you installed WordPress on a Windows IIS7 Server using the URL Rewrite Module 1.1, you may receive a HTTP 550 error when clicking on an inserted image.

Well that shouldn’t happen now should it.

After much agonizing I concluded the problem lies in the images’ permissions that seem to get set when first uploading them to/from WordPress. The permissions of the original uploaded image seem to NOT inherit the correct WP upload folder permissions; This in-turn, blocks access to the original file on the server. When the original file is called from the blog/internet, the server throws a 550.50 URL Rewrite Error. The same error that you see in the above image.

Now time for the strange part. Thumbnails of the original are created by WordPress using this same original uploaded image. They display just fine when inserted and called. These thumbnails inherit the correct permissions of the Windows/WP  folder where they are stored. So the question: Why does the original uploaded image that is stored in the exact same location as the thumbnails not inherit the same permissions? Checking the original image directly on the server against the thumbnails that were created from it confirmed my theory. Hum… perplexing. Is this really a URL Rewrite Error or not?

So what causes the original uploaded image from inheriting the correct permissions? The answer is incredibly simple but also incredibly annoying.

The Setup:

For the record, I’m running WordPress 2.8.4 on an IIS7 Windows server 2008 platform using FAST-CGI with PHP, MY-SQL & URL Rewrite module 1.1. I’m using a custom permalinks structure of “/%category%/%postname%/”. The following is the web.config code I’m using along with the same file for download:

<?xml version=”1.0″ encoding=”UTF-8″?>
<configuration>
<system.webServer>
<rewrite>
<rules>
<rule name=”wordpress” patternSyntax=”Wildcard” stopProcessing=”true”>
<match url=”*” />
<conditions logicalGrouping=”MatchAll”>
<add input=”{REQUEST_FILENAME}” matchType=”IsDirectory” negate=”true” />
<add input=”{REQUEST_FILENAME}” matchType=”IsFile” negate=”true” />
</conditions>
<action type=”Rewrite” url=”index.php” appendQueryString=”true” />
</rule>
</rules>
</rewrite>
</system.webServer>
</configuration>

Download: web.config file-1.0

The Solution:

PHP is the issue, not WordPress. The problem only happens when you use PHP to upload a file.  When you upload a file, PHP sends the file to a temporary directory on the hard drive (for me it’s C:\Windows\Temp) and then copies it over to it’s intended directory.  Once the file has landed in the temporary directory, it is assigned the permissions of that directory.  The problem is when Windows copies that file, it keeps the temporary directory’s permissions and doesn’t inherit that of your web directory’s.  Bingo!!

The easiest way to fix this problem is to add to the temporary directory your intended web directory’s permissions.  In other words, don’t erase the permissions already in the temporary directory, just add the web directory’s permissions to them.  In Windows Server 2008 the two user groups you must add are: “IUSR” & “IIS_IUSRS”.

If you want to change your temporary upload directory, find the “upload_tmp_dir” in your php.ini file and set it to the directory of your choosing (outside your web folders of course), and then add the proper permissions.

So, just create a new folder named “PHP_uploads” in  “c:\<YOUR_PHP_DIRECTORY>\PHP_uploads\”. Now go to your PHP.ini file and  change it to the new location.

After adding the new folder location to your PHP.ini file add the IUSR & IIS_IUSRS permissions to the new upload folder you just created.

After your all done, delete the previous uploaded images from your WordPress admin console and reinsert them as normal.

Your 550.50 error is now no more!