Method 'get_IsClientValid' in type 'Microsoft.SharePoint.WorkflowServices.WorkflowServiceApplicationProxy' from assembly 'Microsoft.SharePoint.WorkflowServices, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' does not have an implementation

Method 'get_IsClientValid' in type 'Microsoft.SharePoint.WorkflowServices.WorkflowServiceApplicationProxy' from assembly 'Microsoft.SharePoint.WorkflowServices, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' does not have an implementation

Issue: After installing SharePoint 2013 Server Service Pack 1, I cannot open my sites. Also the Central Admin isn't working 100%.I cannot open 'Manage Service Applications' . The upgrade also end with an error message. When I open the SharePoint Management shell it shows the below error. 

Method 'get_IsClientValid' in type 'Microsoft.SharePoint.WorkflowServices.WorkflowServiceApplicationProxy' from assembly 'Microsoft.SharePoint.WorkflowServices, Version=15.0.0.0, Culture=neutral, PublicKeyToken=71e9bce111e9429c' does not have an implementation.


Cause: This could of missing binaries of SP1.

Solution: This issue could be of many reasons, In this article I am providing the most common to check.

Solution 1:Ensure to have disk space available on the Drives of server.

Solution 2: Ensure to check the below for confirmation.

1.   Go to C:\Windows\Microsoft.NET\assembly\GAC_MSIL\Microsoft.SharePoint.WorkflowServices\v4.0_15.0.0.0__71e9bce111e9429c\-> Right click on the DLL and go to Details. Ensure the File version should be as below(15.0.4569.1501)

                        

2.   Check in the Control Panel -> Programs and Features -> View Installed Updates->SP1,If it’s not there.

Re-install the SP1 to that problem server

I hope the above information will help you to resolve the issue, in case of any queries/questions regarding the above mentioned information then please let me know. I would be more than happy to help you as well as resolves your issues, Thank you.