I encountered the "server application unavailable" Problem and Solution

Today ProgramFrom the ASP. net Development Server is transplanted to IIS, and the "server application unavailable" problem is reported. Here, I declare that my environment is Windows XP + iis5.1 + ASP. net1.1 + ASP. net2.0.
So I started Google and found many similar situations, but all of them are the same. Basically, it is the solution for Windows2003, which is seldom mentioned in xp. Even if someone asks, it seems that no one answered. No way, the problem always needs to be solved, and reinstallation is not always a panacea.
First, I tried to design the Runtime Library settings in IIS, and changed it to the 2.0 library. Then, some configuration options, including identity authentication and program configuration options, appeared, it has no effect. A little discouraged. Is my IIS really broken? However, because RS is installed on the machine and IIS + 2.0 is also used, this problem does not occur, so I believe it must have been a problem with my configuration. It's okay to try it on another machine. If you want to change the directory, it seems that the directory is different? So I immediately copied the content in the precompliedweb directory and put it under wwwroot to create a virtual directory. As expected, no error was reported. Try again on drive C. There is no problem, and you can try again by putting it back to the original directory. Now I know that the access permission problem should be solved. Therefore, the directory permission is granted to everyone for full control. You can create a virtual directory again. Haha, the reason is finally found. But this still doesn't work. I still don't know what users I need. So I first deleted everyone and added iwam_xxx and iusr_xxx. I try the Users group again, the result is successful. So far, the problem of "server application unavailable" under XP + 2.0 has been solved, but it is strange that this is the reason why the error is reported. It remains to be studied later.