Visual Studio Intellisense not working

This has happened to me a few times and, when it happens, I just don’t know what to check to see if I’ve changed any configuration or what. So I decided to write here a list of possible solutions:

1 – Make your project an application

Sometimes when you use the quick access to a project instead of opening it as an application it is opened as a “folder project”. Then classes are not being compiled and Intellisense doesn’t work.

Solution: Open it using the .sln file or right click on the project main folder and select “Make it an application”.

2 – Error on compilation

Similar to the last one, sometimes an error doen’t let VS to compile your class, try to fix that compiling error and recompile. That should fix it.

3 – Class not being recognized

For some reason I’ve found that when I add a new class to the project right-clicking on App_Code and using “Add Class” or “Add New File -> class” the resulting class is not included in the namespace (no matter which one I write) and doesn’t have intellisense. Instead, if you right click on the project main folder and do the same thing “Add Class” then the class will have Intellisense and be included in the project namespace. I presume this happens when the App_Code has been done manually and not by the project itself.

Solution: Try to make an auto App_Code folder or just add classes using the main folder.

4 – Press Ctrl+Alt+Space

Doing that you can activate/deactivate the auto-selection when the intellisense combos are opened.

5 – Intellisense patch

Most probably this is not your problem, but if your VS2010 Intellisense crashes then you may need to install this patch.

That’s all for now, I will update this with more possible solutions in future.