visual studio not remembering open documents & startup project

This doesn't address the startup project issue, but checking the "Reopen documents on solution load" checkbox fixed the remembering open documents issue for me.

You can change that setting here:

Tools -> Options -> Projects and Solutions -> General -> Reopen documents on solution load

Not sure if that checkbox existed before I upgraded Visual Studio 2017 to version 15.8.3 or if it got reset somewhere along the way

I ran into this problem in Visual Studio 2015. Removing the .suo file in the solution root did not fix the problem. I needed to remove everything under the following directory:

\\SolutionRootFolder\.vs\FolderWithSolutionName\v14\

.vs is a hidden folder and .suo is a hidden file under the v14 folder that must be deleted along with the vbcs.cache folder.

Update for VS2017: The problem still exists in VS2017 with the v15 folder.

In Visual studio 2015 :

Tools -> Import and Export Settings -> Reset all settings

It worked for me.

Happy coding :)

I believe this information all lives in your .suo file and/or .user file. If they've become corrupt, VS will struggle, so it'll revert to the default.

Maybe try exiting VS, deleting the .suo and/or .user files, start VS and set it up how you want, restart it again and see if it remembered the settings.