Minecraft online can't get into a server there's always invalid characters?
Your username is too long.
More than 16 characters are not allowed on servers.
Invalid (or unauthorized) showing in the username…
Do you use a crack account? If so, you may use special characters in the user name which can't be displayed on the servers
No, maybe that's because of minecraft's version is cracked
Is it the official Mojang Launcher?