visual studio 2015 IIS Express cannot debug asp.net 4 project RRS feed

  • Question

  • I was working on 2 projects using VS 2013. Recently I had to switch to VS 2015 and opened these projects in the same. One of the 2 project, which is a .net 4.5 framework version project works fine, and I am able to debug in IIS Express. However, the second project - .net 4.0 project - I cannot debug using IIS express. When I try to debug I get a 500 error

    The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration

    I managed to resolve that particular error with help from this stackoverflow link The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration

    But still I could not debug as I got another error

    Unrecognized attribute 'targetFramework' at this line : in web.config

    I am not able find a solution to this problem. there are some articles which suggest solutions for IIS, but not for IIS Express. I am not able to understand why this happens, as the other project (.net 4.5) works fine, so this is not a problem with IIS express framework config, but project related. I did not make any changes to code whiles moving from vs 2013 to vs 2015. What can I do to debug the code using IIS express in vs2015. preferably by not making changes to web.config as this is working fine on the production server.

    • Moved by 宝宝徐 Monday, November 13, 2017 9:34 AM
    Wednesday, November 8, 2017 6:43 AM

All replies

  • Hi Azhar,

    Thanks for your posting.

    However, this forum is for Visual Studio IDE issues, to your case I suggest you post it at Asp.net forum or IIS forum. Where the corresponding support engineers will help you with it.

    Your understanding and cooperation will be grateful.


    Best regards,


    MSDN Community Support
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    • Edited by Fletch Zhou Wednesday, November 8, 2017 9:42 AM
    Wednesday, November 8, 2017 9:42 AM