Your workshop addons will all automatically be downloaded. This will delete everything and restore your GMod to how it would be if you did a fresh install. If you're not joining a server - and the errors are happening on your local machine - the best way to fix this is to clean your GMod installation. If not - just leave the server and never join again. If you're feeling kind you can tell the server owner that their server is erroring out. You've joined a server - and the server owner has gone crazy and installed every addon they could find - and they're conflicting, or old, and creating errors.Your have an addon installed that isn't compatible with the current GMod version.The script could be conflicting with other scripts, or could just be doing something stupid which is causing the errors. You have an addon installed and the person that made it didn't really know what they were doing.A script is creating errors - there's usually a few of reason for this: