Could not load file or assembly Telerik.Web.UI in ASP.NET

Question

I had telerik version 2012.2.607.35 When I update it to version 2015.2.623.45

I got this error:

Could not load file or assembly 'Telerik.Web.UI, Version=2012.2.607.35, Culture=neutral, PublicKey Token=121fae78165ba3d4' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

I replaced all reference telerik to version 2015.2.623.45 in project references but the error exist yet.

Answer 1

I had a similar problem. I checked the version of the .dll in the bin folder on my website and the version throwing the error. Since the code where the error was being thrown was not my own, I realised the version of the .dll was a dependency of 3rd party code. As it turns out the .dll in my bin had been overwritten with an older version.

Solution was to put the correct version of the .dll in the bin folder (since this was installed with the application initially) seems an update failed to install the newer version.

Answer 2

you should define assembly in web.config file

<dependentAssembly>
    <assemblyIdentity name="YourDllFile" publicKeyToken="2780ccd10d57b246" culture="neutral" />
    <bindingRedirect oldVersion="0.0.0.0-YourDllFileVersion" newVersion="YourDllFileVersion" />
</dependentAssembly>


<dependentAssembly>
    <assemblyIdentity name="Telerik.Web.UI" publicKeyToken="121fae78165ba3d4" />
    <bindingRedirect oldVersion="1.0.0.0-2015.2.600.45" newVersion="2015.2.623.45" />
</dependentAssembly>

Answer 3

While the assembly binding redirect is a way to solve this, as suggested by the answer, I would advise you to find the fully qualified assembly reference and make it non-fully qualified. It is likely to be a Register directive in the web.config or in a user control. Doing that will make future updates easier, otherwise you will get the same error the next time you upgrade unless you also update the bindingRedirect.