Quick Summary
The 'Failed to login: Invalid session' error in Minecraft usually indicates that your game client's session ID doesn't match the one stored on the Minecraft servers. This mismatch can occur due to a variety of reasons, often related to authentication or connectivity issues.
Common Causes
- Session Data Corruption: Your Minecraft session data has become corrupted or outdated, preventing the game from properly authenticating with the servers.
- Launcher Issues: Problems with the Minecraft launcher itself, such as incorrect or missing updates, can lead to authentication failures.
- Internet Connectivity Problems: Intermittent or unstable internet connectivity can interrupt the authentication process, resulting in an invalid session.
- Multiple Minecraft Instances: Running multiple instances of Minecraft with the same account simultaneously can invalidate the session for one or more instances.
- Firewall or Antivirus Interference: Firewall or antivirus software might be blocking Minecraft's access to the internet, thus preventing proper authentication.
- Mojang Server Issues: Less frequently, the problem may lie with Mojang's authentication servers encountering temporary difficulties.
Step-by-Step Fixes
Method 1: Restart Minecraft and the Launcher Show Steps ↓
Step 1: Completely close both Minecraft and the Minecraft Launcher.
Step 2: Wait a few seconds to ensure all processes have terminated.
Step 3: Reopen the Minecraft Launcher and try logging in again.
Step 4: Launch Minecraft and check if the issue is resolved.
Method 2: Restart Your Computer Show Steps ↓
Step 1: Save any work in progress and close all programs.
Step 2: Restart your computer.
Step 3: After the restart, open the Minecraft Launcher and attempt to log in.
Method 3: Relogin to Your Minecraft Account Show Steps ↓
Step 1: Open the Minecraft Launcher.
Step 2: Log out of your Minecraft account within the launcher.
Step 3: Close and reopen the launcher.
Step 4: Log back in using your Minecraft account credentials.
Step 5: Launch Minecraft and test if the issue is fixed.
Method 4: Check Your Internet Connection Show Steps ↓
Step 1: Verify that you have a stable internet connection by browsing the web or using other online applications.
Step 2: If you are using Wi-Fi, try switching to a wired connection (Ethernet cable) for a more stable connection.
Step 3: Restart your modem and router.
Step 4: Check that Minecraft and the Java Runtime Environment (JRE) are not blocked by your firewall.
Method 5: Delete the 'authlib-injector' file Show Steps ↓
Step 1: Close Minecraft.
Step 2: Open your .minecraft directory/folder. The defautl location is C:\Users\YOURUSERNAME\AppData\Roaming\.minecraft
Step 3:Locate the 'authlib-injector' file and delete it.
Step 4: Restart your computer and the error should be resolved.