While upgrading to 7.6 the following error was encountered after enabling the 'Next' button in SIM via registry key.
Installing: 3 of 121 components: Platform Core 7.6 x64 (7.6.1383)
Failed to configure NS.
Failed to change script map for the agent virtual directory.
"Failed to configure NS."
"Failed to change script map for the agent virtual directory."
IIS script maps for ASP.NET are missing or misconfigured. Current implementation of ASP.NET 4.5.1 Install Readiness Check is code from a similar check that was written for IIS 6.0. It utilizes IIS6.0 metabase compatibility API and does not work at all if IIS7 was configured to use some features that were not supported in IIS6 (IPV6 for example). It was tested only with minimal default installation of IIS7.
Fix is tentatively targeted for SIM version 8.0 HF1 (post 8.0.53).