Sorry, unable to start Minecraft. Please check your configuration and try again.

When I tried to update Minecraft from 1.16.2 to 1.16.3, the launcher said that the newest version of Minecraft was my 1.16.2 version of optifine I had installed. When I went to make a new instance of Minecraft, no new versions showed up at all. So I tried to re-install the launcher. That didn't work. The next thing I did was a clean re-install of all Minecraft. (deleting the program files) that didn't work. So as a last-ditch attempt I did a fresh start on my pc. (I had needed to for a while anyway) and somehow that didn't work either. What the hell is going on?