Ever wondered why suddenly you cannot debug because the compiler isnt breaking on your breakpoints.
There are several reasons for this.
make sure that.
1. Your project is compiling when you begin debugging (check this in build > configuration manager)
2. Ensure your projects are compiling in debug mode not release (check this in build >configuration manager)
3. In the Webconfig ensure you are in debug mode
<compilation debug="true" strict="false" explicit="true" targetFramework="4.0">
4. The (project properties > startup options > debuggers has the ASP.NET checkbox checked)
5. Delete all pdb files in your bin folder
6. Ensure every project referenced is set to build under (build > configuration manager)
7. Do a full clean and rebuild. (build > clean solution) (build > rebuild solution)
Finally and this is the one that caught me out
8. Check you are not setting a cookie cache timeout of positive time, I was expiring my page after 1 day. The best way to check this is to load a page in debug, knowing your break point will not be stopped at. Once the page is fully loaded hit ctrl F5 to force full reload of the page. If your breakpoint is stopped at then you know its a cache problem.