Numerous players have encountered "Invalid Session" errors while trying to connect to Minecraft servers, both for servers they own and servers they are trying to join, when booting using TLauncher. The issue stems from licensed server data checking whether or not the player is authorized under the Minecraft license, and has a few fixes you can try.

There are two separate error messages that you may be receiving, both of which can be resolved with the same troubleshooting methods. You may be seeing "Failed to login: Invalid session (Try restarting your game and the launcher)", or alternatively, "Failed to verify user name!". Both of these errors relate to the server failing to authorize you under the Minecraft license, as TLauncher doesn't require you to log in using a licensed Minecraft/Mojang account.

RELATED: The Vatican Has Its Very Own Minecraft Server

Failing to Connect to Another Server

When trying to connect to servers hosted by other people, if you receive any of the aforementioned error messages, that means that the server, unfortunately, requires that you have a licensed Minecraft account to connect. If you really want to connect to that particular server, you're going to have to purchase the licensing and create a Minecraft account on minecraft.net. Once you have an account set up, you can log in under the "Accounts" menu in TLauncher with your credentials and should then have free access to any of these servers.

If you aren't willing to throw money down on an account, then you'll have to find a new server: one that doesn't check for a license (a cracked server). Luckily, there are more than 700 to choose from. These servers should not return an error message as they are not checking for authorization when you attempt to join.

Failing to Connect to Your Own Server

When creating a server, they will always default to checking for authorization under the Minecraft license. Luckily, as this is your server, you have the power to change that. Under the "server.properties" file in the server folder, do a ctrl+F search to find the "online-mode=true" line. You're going to want to change "true" to "false". This will disable license checks and allow you to connect to the server.

If you're using other server hosting services, such as Aternos, Apex, etc., you can find the relevant menu items in the hosting interface to change the settings there. You're going to want to look for "online-mode", "Cracked Client Access", "License Check", etc. The name will vary by service, but all mean the same thing. Disable these settings to turn your server into a cracked server, allowing you to connect.

Source: TLauncher

MORE: Minecraft Players Discover Title Screen World After Almost 10 Years, And It's Breathtaking