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"Failed to Login: Bad Login" error


When you connect to a Minecraft Server, your Minecraft client sends data about your current authentication session to the Minecraft Server. The Minecraft Server then contacts Mojang’s authentication servers and asks if the authentication data is valid.

If the authentication data is not valid then you will get the error:

Failed to Login: Bad Login



  • Your current authentication session has expired
  • You logged into a second Minecraft launcher which started a new authentication session. The first launcher’s session is therefore invalid
  • You are connecting to a Minecraft server of version 1.6.4 or earlier using the current official Minecraft launcher
  • There may be a problem with Mojang’s authentication servers. Check here:



Invalid/expired session

If your authentication session has expired, or has been invalidated by another launcher you can create a new authentication session by restarting your Minecraft launcher. You may need to log out and back in again to make sure you get a new session. More help can be found here


Minecraft 1.6.4 and earlier

If you are connecting to a Server running Minecraft 1.6.4 or earlier, then the current official Minecraft Launcher fails to pass the authentication session ID to the client. There are some workarounds:

  • For un-modded Minecraft, run Minecraft from the AT Launcher
  • Run FTB Modpacks from the Legacy FTB Launcher
  • Disable Online Mode on the Minecraft server


Run Minecraft from the ATLauncher

You can set up a vanilla Minecraft client instance in ATLauncher:

  1. Open AT Launcher
  2. Click on the Packs button on the right hand menu
  3. Search for Vanilla Minecraft in the list
  4. Click on New Instance
  5. Choose the version of Minecraft you wish to install
  6. Optional: Alter the name of the instance (you may want to add the version number)
  7. Click Install
  8. Click Install again on the Select mods to install window
  9. That version of Minecraft will be installed, click OK when it is done
  10. Click on the Instances button on the right hand menu
  11. Find your new instance in the list and click Play


Run FTB Modpacks from the Legacy FTB Launcher

The Curse/Twitch launcher uses the Minecraft launcher. If you want to play an FTB pack, you can use the Legacy FTB Launcher:


Disable Online Mode on the Minecraft server

Disabling Online Mode on a Minecraft server stops the server from contacting the Mojang Authentication server. However it also means that players can join using hacked Minecraft clients and their identity cannot be trusted. It may allow players to get Op status on your server and cause havok.

  1. Open the Multicraft Control Panel
  2. From the left hand manu click Files and then Config Files
  3. Click on Server Properties at the top of the list
  4. Look for Online mode
  5. Set it to Disabled (If it is a text field, type in false)
  6. Click Save at the bottom of the page
  7. Restart the server


keywords : bad login, Failed to Login, Legacy FTB Launcher

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