This article will guide you on how to configure phpMyAdmin in Windows Server 2003 Operating System if it is showing an error, as illustrated below – 
Refer to the below-mentioned steps to resolve this error –
1. Allow FastCGI from the following option in IIS, as shown in the figure below.
[Start → Administrative Tools → Internet Information Services Manager → Expand Web Service Extensions from left pane → right click on FastCGI → Select Allow]:
2. Right-click on the website phpMyAdmin and select Properties.
3. Go to the Home Directory tab and click on Configuration.
4. Select Add option from the opened Application Configuration window.
Here, you need to add the .php extension at the executable path C:\WINDOWS\system32\inetsrv\fcgiext.dll by browsing it from the Browse button.
Also, set the appropriate limit, as shown in the figure below –
6. If not added, you can also add an index.php file from the Document tab as a default page.
7. Click on Apply and OK to close all the consoles.
Now, you can access phpMyAdmin, without any errors.
