MissingMethodException Workflow Activation CRM Troubleshooting

Sometimes after we upgrade our CRM version to SP1, we have error when you try to Activate a SLA:

MissingMethodException 
   Method not found: 'Void Microsoft.Xrm.Sdk.Workflow.Activities.StartChildWorkflow.set_InputParameters

(System.Activities.InArgument`1<System.Collections.Generic.Dictionary`2<System.String,System.Object>>)'. at 

Microsoft.Crm.Dialogs.ActivateDialogPage.ConfigureForm() at Microsoft.Crm.Application.Controls.AppUIPage.OnPreRender(EventArgs e) at 

System.Web.UI.Control.PreRenderRecursiveInternal() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean 

includeStagesAfterAsyncPoint)  
   http://172.30.101.6:5555/CRA/_grid/cmds/dlg_activate.aspx?iId={2644DE6B-F006-E511-93FD-00155D64E803}&iIndex=0&iObjType=9750&iTotal=1 
   /CRA/_grid/cmds/dlg_activate.aspx 

Cause:

You have restarted the AsyncService and it won't help.

It is actually caused by your CRM Server still stores the old Microsoft.Xrm.Sdk.Workflow.dll assembly version.

It is different from your dll inside the CRMWeb/bin folder.

If you notice its version is still 6.0.xxx..... while the SP1 should start from 6.1.xxx

Solution:

You have restarted the AsyncService and it won't help.

So, you need to replace the old dll with the new one from your 'C:\Program Files\Microsoft Dynamics CRM\CRMWeb\bin' folder..

If you cannot just copy and paste to overwrite the file, you might need help from gacutil command

At first, please backup first the DLL, just in case something happened after you uninstall it.

Then, please check this one:

gacutil /l Microsoft.Xrm.Sdk.Workflow

If it has no of items = 1, means you can uninstall it, please continue and uninstall it by this command:

gacutil /u Microsoft.Xrm.Sdk.Workflow

Here is the screenshot

To run the GACUtil, you might need refer to this:

https://msdn.microsoft.com/en-us/library/ex0ss12c%28v=vs.110%29.aspx

*If you can't find the gacutil because you have no Visual Studio, you can install the Windows SDK, if not also, do not worry, you do not need all of this, as long as you have installed the .NET Framework (which I am sure all of you have installed it)

Just go to the C:\Program Files <x86>\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools>

> So the sequence commands:

cd  C:\Program Files <x86>\Microsoft SDKs\Windows\v8.0A\bin\NETFX 4.0 Tools>
gacutil /l Microsoft.Xrm.Sdk.Workflow
gacutil /u Microsoft.Xrm.Sdk.Workflow

After you uninstall it, you can copy paste your newer version dll inside its folder

And see that this will save your day

Hope this helps!
Thanks.