Due to technical restrictions, the Modrinth App does not currently support Forge installations on Minecraft versions 1.5 through 1.6.4. Additionally, on Windows only, 1.5.2 or older will not work, even with a Vanilla instance. This is a known issue, and we are working on fixing it.
⛔ As of January 2024, certain Forge versions for newer Minecraft versions (1.20, 1.20.1, 1.20.2, 1.20.3, 1.20.4) are also known to be broken. This is known and will be fixed soon.