What should I do if I encounter the "server application unavailable" problem ???

Solution 1: batch processing:

Cd c :\
Net stop w3svc
Cd C: \ WINDOWS \ Microsoft. NET \ Framework \ v2.0.50727
Aspnet_regiis.exe-ua
Aspnet_regiis.exe-I
Net start w3svc

Run it.

Solution 2: Create an application pool:

To create an application pool
1. Click Start, point to program, and click Control Panel ".
2. Double-click "Administrative Tools" and double-click "Inte. Net Information Service (IIS )".
3. Right-click application pool, point to new, and click application pool ".
4. Type AppPool1 in the application pool ID text box.
5. Click OK ".

Allocate applications to the application pool
1. Click Start, point to program, and click Control Panel ".
2. Double-click "Administrative Tools" and double-click "Inte. Net Information Service (IIS )".
3. Double-click "Web site ".
4. Double-click "Default Web site ".
5. Right-click DebugApp1 and click Properties ".
6. In the "main directory" tab, select "AppPool1" in the "application pool" list box, and click "OK ".

Solution 3: Modify the access permission of the folder where the website directory is located:

Right-click the current website directory and choose Properties> Security> Add> advanced> Search now> select UsersUser-> OK