What are the potential ways to safely close an app on Windows shut down so that it won't give an error next time I open it? I have an app that executes on Windows start and runs in the background and I don't feel like closing it each time I shut down Windows, so I'm seeking other means to automatically close it on Windows shut down.
The PortableApps.com Platform can be used to automatically shut down all your portable apps safely, including those not in PortableApps.com Format, and warn you if any can't be, on clicking the platform's power button which triggers a Windows shutdown selection (shutdown, restart, or logout).
Sometimes, the impossible can become possible, if you're awesome!
There is a variety of methods, depending on the version of Windows. You also need to consider including what the application does and how the application is written? e.g. What are it's specific shutdown requirements, does it need to save data/settings prior to closure. The PortableApps platform does, of course, already have built in protection and recovery techniques for supported applications (i.e. apps officially released in PortableApps Format).
It's a given, whatever method you choose to employ, if you fail to close down all applications correctly software and/or data loss/corruption is a high probability.
Google the question and you will find numerous guides applicable to each version of Windows.