You only need to do this if you're prompted by the launcher, with an error similar to this:
To fix your hosts file:
- Open Notepad as administrator (right click, Run as administrator)
- Click File -> Open
%systemroot%\System32\drivers\etc\hosts(you can copy and paste that into the "File name" box)
- Delete the lines that don't start with a
#, then save the file (File -> Save)
- After that, just login as normal.
If the steps above don't fix your issue, drop by our Discord server for help: https://discord.gg/technic, join the #tech-help channel.