When developing c# apps sometimes we import and use external dll's that may have dependencies from another dll's.
When you do that you might encounter an error of type "The located assembly's manifest definition does not match the assembly reference".
For instance, In a project I'm working for I had this error:
What this means is that the framework was looking for an assembly called WebGrease with a version 18.104.22.168624, but the version I have on my solution was 22.214.171.12434.
To fix this I added an assembly binding in web.config by forcing an old version to look for a new version (in my case the version 126.96.36.199.234 for the WebGrease dll) as you can see in the pic below:
Doing this fixed my problem:
Hope this helps someone :)