Check your local instance
Check the files.
Keep them on your computer.
Select a Minecraft instance or a few manifest and log files. Your browser checks them for common Verity problems and shows what to try next.
The tool reads selected filenames, manifests, and a limited part of latest.log. The files stay on your computer.
The tool cannot change the instance. It ignores worlds and API keys, and it never starts a download.
What it can spot
The checker recognizes Verity JAR names, Forge, NeoForge and Fabric, Minecraft 1.20.1 and 1.21.1, missing GeckoLib, provider login and quota errors, Ollama connection failures, and Forge files placed in a NeoForge instance.
What to select
In Chromium, you can select the instance folder. In another browser, choose the mod filenames, instance manifest, and latest.log. The tool reads a limited number of files and a limited amount of log text. It ignores worlds and does not send the files to a server.
Check the result
Compare the project and loader it found with the version table, then use the troubleshooting guide. If nothing matches, keep the clean profile and look for the first useful error in the log.