IIS8 refuses to run .aspx pages(404 error)

I installed MS Exchange on windows 2012 server r2and I just can't run OWA from it.

Trying to run it leads to the following message : HTTP Error 404.3 - Not Found

Detailed error information:
Module : StaticFileModule
Notification : ExecuteRequestHandler
Processor : ExecuteRequestHandler
Error Code : 0x80070032

I know the file(s) exist, and I installed ASP.NET 2.0, 3.5, 4.0
I also ran aspen_regiis.exe -i and I ticked the 'Allow undescribed(?) ISAPI Modules' in the ISAPI limitations(?).

Please note that some of the error messages aren't the same in English version of IIS8(aka I'm using the FOREIGN version of IIS8). The aspx page is written in (probably) ASP.NET 2.0

You should install IIS sub components

go to Control Panel -> Programs and Features -> Turn Windows features on or off

Internet Information Services has subsection World Wide Web Services / Application Development Features

There you must check ASP.NET (.NET Extensibility, ISAPI Extensions, ISAPI Filters will be selected automatically). Double check that specific versions are checked.

Run from cmd:

%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_regiis.exe -ir

Finally check in IIS manager, that your application uses application pool with .NET framework version v4.0.