How do I copy modified DLL files to my website?

I am developing a website using Microsoft Visual Studio and IIS. I develop on one computer and am now trying to deploy modified compiled C# assemblies to the server. The following is what I have done and what happened.

1. I made a copy of the MY.DLL that I was going to change in the same website BIN folder COPY_OF_MY.DLL.
2. I copied the new modified MY.DLL to the production server.
3. I try to access the website and I get an error that it cannot load COPY_OF_MY.DLL.
4. I rename the new MY.DLL in the same folder to MY_NEW.DLL, and rename COPY_OF_MY.DLL back to MY.DLL.
5. Trying to load the website it now complains about being unable to load MY_NEW.DLL.
6. I delete MY_NEW.DLL.
7. Trying to load the website I now get an error as below:

erver Error in '/' Application.
Configuration Error
Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.

Parser Error Message: Could not load file or assembly 'Microsoft.Web.Services3, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.

Source Error:

Line 210:                        <add assembly="System.DirectoryServices.Protocols, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
Line 211:                        <add assembly="System.Web.RegularExpressions, Version=2.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
Line 212:                        <add assembly="Microsoft.Web.Services3, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/></assemblies>
Line 213:            </compilation>
Line 214:            <!--  CUSTOM ERROR MESSAGES


Source File: C:\Inetpub\wwwroot\AspDotNetStorefront\Web\web.config    Line: 212

Assembly Load Trace: The following information can be helpful to determine why the assembly 'Microsoft.Web.Services3, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' 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].

What have I done wrong? How do I correctly deploy modified assemblies to my web server?Start Free Trial