Server Error in 'which application is worth noting

When you access an ASP. NET site, the following error is reported on the page:

 

The problem is that there is a problem with Web. config. Open the Web. config file under the site root directory (Home Directory) under IIS and follow the prompts to modify the file. After modification, no effect is found.

 

Let's take a closer look at the problem. The server error in '/_ layouts' application is not the server error in '/' application that we usually see. in fact, the web under the _ layouts virtual directory (virtual directory) should be modified. config.