Roblox not working is a common problem in 2021. So here are some solutions that can resolve this issue to get Roblox working for you again ...

Fix #5: Whitelist Roblox in your firewall settings. If your machine’s firewall is actively blocking your Roblox game, it may also lead to players being unable to log in or find their game servers.

Fix #3: Update Roblox installation files. If Roblox is still showing the same crash error, the final solution that you can try is to update certain files in the installation folder.