Mojang forgot the tweak class in the a1.2.6.json
This is the original line in the a1.2.6.json:
"minecraftArguments": "${auth_player_name} ${auth_session} --gameDir ${game_directory} --assetsDir ${game_assets}",
This is wrong.
It should be:
"minecraftArguments": "${auth_player_name} ${auth_session} --gameDir ${game_directory} --assetsDir ${game_assets} --tweakClass net.minecraft.launchwrapper.AlphaVanillaTweaker",
When you join in a multiplayer server, your name is Player524.
Comments 2
Is this still a concern in the current Minecraft Launcher version 2.0.805 / 2.0.806? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases. If this has been done, we can reopen the issue.
Keep in mind that the "Resolved"-Status on this ticket just means "Answered", and that we are waiting for further information on whether this issue still exists or not. It will be reopened it as soon as the requested information has been delivered.
Confirmed! I joined my local server and my name was Player524.