I don't see any error, do you have more information? It's seems it's looking for a Forge installation but it does not find one, maybe you're not installing optifine on a matching vanilla profile? Which launcher are you using?
The official launcher. (With the official purchase) I'm using optifine version 1.16.4. It doesn't have forge (i'm using twitch forge launcher for modded play.) and it has no mods except for optifine. Does Optifine needs forge in order to run? It runs part of the time and gives an error some other times. I can still play with optifine, however, it only launches part of the time. Also, I have a microsoft account. Thanks.
Hi TitleEntity, I downloaded the 1.16.4 forge link and clicked on the forge profile through the official minecraft launcher. I tested first without forge and then put Optifine in the mods folder. It worked, and no errors so far! (I'll let you know when I encounter more errors in my minecraft. Thanks so much! By the way Optifine isn't listed under the mod list in the minecraft title screen, is it supposed to do that?