Failed to access IIS metabase ASP.NET

Failed To Access IIS Metabase Error In ASP.NET, If You are getting "Failed to access IIS metabase" error while browsing asp.net site or aspx page in IIS server then you may have installed IIS Server after installing the .NET framework.

If that's the case, try running to repair your ASP.NET installation and set up all of the appropriate ISAPI extension mappings.

Open visual studio command prompt and type this command

aspnet_regiis -ga \username
username is usually aspnet

if this doesn't work than use this command

aspnet_regiis -i

alternatively you can copy and paste this command into windows command prompt

%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i

this will fix your problem
Ref.