When you are developing server side architecture & deploying web applications, it is crucial to have errors report as much information as possible to aide in the development and debugging process. The scripting language you are using will have its own error reporting configuration, but in the case of windows servers, it is necessary to set up the Windows IIS debugging and error reporting as well.
Here is a great guide from iNet with directions & photos that will have you configuring detailed error messages for IIS in only a minute!
The power of having detailed and specific error messages is one that no developer can do without. When dealing with web applications on windoes servers, there are certain quirks and obstacles that can make it difficult for the average developer to achieve optimal results. Enhacing the debugging process by enabled more detailed error messages will certainly aide in this process.
Remember to reset these properties when the website it ready for public launch. Providing so much detail in errors to the user is bad practice and extremely risky as it is prime information for any potential hacker.