If when installing Captools/net on a 64-bit version of MS-Windows, the IIS fails to run with a 503 error indicated, this may be due to the need to register the 32-bit version of ASP.NET:

 

Run this command to perform the registration:

 

%SYSTEMROOT%\Microsoft.NET\Framework\v1.1.4322\aspnet_regiis.exe -i

 

 

Reference: http://support.microsoft.com/kb/894435

 

 

Also, following a Windows update a 503 error may be encountered due to orphan symbolic links left by the update process.  These can be resolved as follows:

 

https://support.microsoft.com/en-us/help/4050891/error-http-503-and-was-event-5189-from-web-applications-on-windows-10

 

The Microsoft web page explains what to do with the IIS 503 error after the bad windows update.

Important!:  One line in the instructions is crucial for the powershell command to work, “To resolve this problem, manually delete the symbolic links that are created by Windows Update.” This means going into the folder C:\inetpub\temp\AppPools and there will be a folder shortcut to something called CTNetAppPool. This shortcut needs to be manually deleted before the powershell command will actually do what needs to be done. When the powershell command is executed a bunch of the .tmp files will be gone and a new actual folder, as opposed to a folder shortcut, will be created in there called CTNetAppPool. Inside that folder will be an xml file that is required.