You may not be able to log in to Tekkit due to a damaged cache or Technic Launcher installation. In addition, an outdated Minecraft installation may also cause a current connection failure. The affected user has an error when trying to participate in a multiplayer game or trying to connect to the server. The problem may occur on Windows, Mac and Linux. In some cases the user has encountered a problem after updating his Tekkit server. The error affected most users who have migrated accounts.
Before troubleshooting, make sure that all Minecraft servers are enabled and working to remove the error message. Also make sure that your internet connection is working correctly. Also make sure that Java is updated to the latest version.