Bug/Issue Game Doesn't Launch - Reinstalled - Error Log Included (FIXED)

I was playing fine just a couple of weeks ago. Today, I sat down to play, fired up GOG Galaxy (1.2.26) on Windows 10, as per usual. Hit Play on Stardew Valley, and the button goes from green to grayed out. The "Syncing Cloud Saves" text shows up next to the More button. A small notification says "Synched with GOG Galaxy Cloud" in the bottom right corner. The Play button goes from grayed out to green again. The game never launches.

I've rebooted. I've reinstalled Stardew Valley. No dice.

I uninstalled GOG Galaxy and Stardew Valley, not keeping any user data/save files then reinstalled both to new locations.

It's still doing the same thing.

 

I've also tried launching it without GOG installed. There's a momentary spinning icon, then nothing. It doesn't launch.

I found the error log. Here's what it says:

Message: Sequence contains no elements
InnerException:
Stack Trace: at System.Linq.Enumerable.Last[TSource](IEnumerable`1 source)
at StardewValley.Options.setToDefaults()
at StardewValley.Options..ctor()
at StardewValley.Game1.LoadContent()
at Microsoft.Xna.Framework.Game.Initialize()
at StardewValley.Game1.Initialize()
at Microsoft.Xna.Framework.Game.RunGame(Boolean useBlockingRun)
at StardewValley.Program.Main(String[] args)

 

I've also tried launching it without GOG Galaxy installed. Same thing.

 

I contacted Stardew Valley Support and got these instructions to try, which did not work for me:
(1) Delete the startup_preferences folder in %AppData%/StardewValley
(2) On this site (http://freewisdoms.com/download-dll-files-commonly-used-by-games/) you can download a package and then try to insert the downloaded SysWOW64 and the System 32 folder into the Windows folder.

Today, I noticed that both Windows and Avast had updates. I let them both update and VOILA! It's working again! Not sure if it was one of those two, but that seems likely.