Can not load assembly for 'Microsoft.Owin'

Question

I have an issue in asp.net web API where when I add Signlr class I get. I can see in the references Microsoft.Owin

Could not load file or assembly 'Microsoft.Owin' or one of its dependencies. >The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Exception Details: System.IO.FileLoadException: Could not load file or assembly 'Microsoft.Owin' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

Solution 1

It seemed like you confused with SignalR project development. Please read this article.

Solution 2

I suggest to check what you have in packages.config, web.config and packages folder. They all should link to the same package version. Quite often if you update version of some package via NuGet, there may raise compability issues. P.S. If it not help you may delete and istall OWIN again via NuGet.

Comments

[MohamedAbbas]

i have deleted it and installed it again but i still cannot find owin startup class !

[andrey.shedko]

Did you check your packages.config, web.config and packages folder?

[MohamedAbbas]

in the i find packages.config <package id="Microsoft.Owin" version="2.1.0" targetFramework="net45" />

[MohamedAbbas]

and in all files you mentioned

[andrey.shedko]

So you're sure that everywhre it reference to the same OWIN version? Ok. Did you re-build solution after you update OWIN via NuGet?

[andrey.shedko]

What is in your bin folder? Is it the same OWIN version? You may see your bin folder if you press Show All Files in Solution Explorer.

[MohamedAbbas]

Now i have removed Signlr package and just installed OWIN after i build and run i found no error but still can not find Startup class

[andrey.shedko]

If I understand what you mean correct, Startup class you must create manually. Here is about Startup class - asp.net/signalr/overview/signalr-20/….

[MohamedAbbas]

Yes in the bin folder they are the same

[MohamedAbbas]

so now i create the Startup class and add signlr package !