KB14168: ‘Server Application Unavailable’ error occurs and the ASP.NET user account locked out when users attempt to access MicroStrategy Web 9.x

SYMPTOM:
When users attempt to access Strategy Web 9.x, the following error occurs:
 

 
Server Application Unavailable
The web application you are attempting to access on this web server is currently unavailable. Please hit the "Refresh" button in your web browser to retry your request.
Administrator Note: An error message detailing the cause of this specific request failure can be found in the system event log of the web server. Please review this log entry to discover what caused this error to occur.
The following error message also appears in the Application event log:
 

 
aspnet_wp.exe could not be launched because the username and/or password supplied in the processModel section of the config file are invalid.
CAUSE:
The process model user account, which is ASP.NET by default, has been locked out.
 
ACTION:
The Administrator needs to unlock ASP.NET user. To do this, follow the steps below:
 

1. Go to Control Panel -> Users and Passwords -> Advanced tab.
2. Click on the 'Advanced' button from Advanced User Management.
3. Click on the users folder and right-click on ASPNET user.
4. Click on Properties and uncheck the 'Account is locked out' option.