What causes a missing .ini file error in TTWeb?

This error is usually caused by the URLScan filter in IIS.

This problem can be overcome by changing the setting in the urlscan.ini, that can be found in the \System Root\System32\Inetsrv\Urlscan\ folder. You will need to remove .ini from the [DenyExtensions] section and add it to the [AllowExtensions] section.

You will also need to do the same with the .exe extension. You will need to restart IIS for the changes to take effect.