I am testing a Web site on my local PC. This is Windows 8.1 with IIS 8.5. I already have an application defined in IIS which points to that directory and that works fine. Now, I created another application pointing to that same directory and using the same application and I cannot connect to the databse.

The error is "Login failed for user 'NT AUTHORITY\IUSR'.".

The application is set up to use the same application pool. I do not know why the new application I created in IIS is not using the application pool account which is specified.

Anyone can explain that?

Basically, lets say I have d:\IIS\MyTestWebSite.

In IIS, I have one application pool. I have one application defined for that directory. This can connect to the database. The application name is LevelExtreme20. Now, I create LevelExtreme15, which is also pointing to d:\IIS\MyTestWebSite. That one also uses the same application pool. So, the application remained as is. Thus, the credentials are already in there. However, when running that Default.aspx page, as soon as it has to connect to the database, it fails as it tries to use a different account. That is not the account defined in the application pool.