VJSCOR Assembly frequent error only in UAT environment Not in PROD

Hi Guys,

I am getting the below errors frequently whenever any deployment or after 40 minutes I am getting the below error only in UAT environment. But not in Production Environment . All codes are same in UAT and Prod.

Please suggest any solution

Could not load file or assembly 'vjscor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.IO.FileNotFoundException: Could not load file or assembly 'vjscor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.

Source Error: 

Line 38: <form id="form1" runat="server">
Line 39:Line 40:     <asp:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">Line 41:     </asp:ToolkitScriptManager>
Line 42: 

Source File: D:\Projects\AEDDO\login.aspx    Line: 40 

Assembly Load Trace: The following information can be helpful to determine why the assembly 'vjscor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' could not be loaded.

WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].