Web.config Build vs Release transform not working

Then I Build the solution (just via Build or even via a complete rebuild (e.g. Clean, Rebuild)). I upload the newly built DLLs to the webserver, as well as the Web.config and Web.Release.config files

There is your error: Web config transforms won't work for your local environment, if you simply build. You need to publish.

Your deployment process seems weird: You are only copying DLLs, Web.config and web.Release.config. To me it seems, that you copy your source code and not a compiled application. A published WebApplication doesn't contain a web.release.config.

You should publish your project (rightclick on your WebApplication -> Publish) to your local filesystem and copy the files from there, or use another deployment method of your choice.

2 years ago I wrote an article about web.config transforms. It gives you a step-by-step tutorial for VS 2010 (The publish dialog changed in VS 2012): http://www.tomot.de/en-us/article/5/asp.net/how-to-use-web.config-transforms-to-replace-appsettings-and-connectionstrings

You can try the Slow Cheetah plugin:

http://visualstudiogallery.msdn.microsoft.com/69023d00-a4f9-4a34-a6cd-7e854ba318b5

This will let you see the transformations 'live' by giving you an extra context menu option. Right-click and choose Preview Transform to see the transformation without having to do a build. Its also really handy for implementing app.config transformations

I thought transformation is only done when you publish the site/app.It is not done when building an application. The latter would constantly change the web.config under source control (which would be a real hassle)