As often a solution to a strange error is so simple when you know it.  When I copied my add-ins to a  new computer I was not able compile the objects that included DotNet add-ins.


As this happened when I was installing NAV 2013 R2 for the first time my first thought was that this was something that had changed between versions and I sent a support request to Microsoft.

Mohamad Vajid and Duilio Tacconi took the case and tried to reproduce the problem without success.  Yesterday we took a look at the problem together and the solution came to our attention.

The Add-in was copied from a web site and because of that the file was blocked by the server operating system.


Then today as I was creating a new website with files that I downloaded from the web I had the same problem.  That will be the last time.

After you unblock the file, recheck to see if that worked.  If the file is in a protected folder you might need to drag it to your desktop to unblock it and back again.

Thank you Mohamad and Duilio for the assistance.

10 thoughts on “Could not load type “. error in DotNet object

  1. wakestar says:

    I reported exactly this problem back in june to microsoft and I got the solution after a few weeks. It should be a known issue.

  2. Dave Machanick says:

    Thanks Gunnar.
    Being a dotnet lightweight. I wondered what I was doing wrong, then found your solution.


  3. I hit this problem as well, and the solution I used to fix it was streams.exe that can be downloaded from technet:

    1. Thank you.

      I am now using powershell to make sure none of the files are blocked.

      1. Devesh says:

        Hi Gunnar,
        Sorry any idea what is the solution please, I am getting similar error.

        “Could Not load type “.

        1. Have you unblocked the dll file?

  4. Chris Collins says:

    Hi, I’m having the same error message occur with NAV 2015 and an add-in I’ve created. I have been developing an add-in and so far, all was working well. Now, for some reason, the error message appears. There is no option to unblock.

    Any ideas?



    1. A Client Add-in might need to be recompiled with the UI Framwork from the 2015 DVD. Is that the case here ?

  5. Chris Collins says:


    Thanks for the reply. It is using the UI Framework from the 2015 DVD. The add-in was working fine in 2015 but it is constantly under development at the moment and for some reason just stopped working in NAV. I am going to try the latest CU of 2015 and see if that makes a difference but I am not hopeful.



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