Fix "Failed to verify username" on Minecraft

A player is disconnected with Failed to verify username! because your server is in online mode and Mojang did not confirm that the player signed in with their own account.

Checked against Minecraft 26.3 (Mojang's own server and language files), October 2026.

What the error means

Joining an online-mode server takes two steps. The player's game tells Mojang's session service that it is joining, then your server asks the same service whether that player really did (this is what minecraft.wiki's protocol page describes). If Mojang has no matching join to report, your server disconnects the player with Failed to verify username! and writes this line to the Console:

Username 'Steve' tried to join with an invalid session

Other messages look similar but point somewhere else:

• Authentication servers are down. Please try again later. Sorry! The server could not get an answer from Mojang. Wait a few minutes and have the player try again.
• Invalid session (Try restarting your game and the launcher) The player's own game could not start a session. Restart both, as the message says.
• Multiplayer is disabled. Please check your Microsoft account settings. The player's Microsoft account has multiplayer switched off.
• You are banned from playing online The account is banned from online play, so no online-mode server will take it.
• You are not white-listed on this server! The whitelist is on and the name is not on it. See Minecraft whitelist: add players, set ops.

Fix it for the player

1. Close Minecraft and the launcher completely and open them again, as the Invalid session message above suggests.
2. Make sure the launcher is signed in to the Microsoft account that owns Minecraft: Java Edition. An online-mode server only lets in players that Mojang verifies, so a launcher without a purchased account cannot get in.
3. Join again from the Multiplayer list.
4. If it still fails, check the server settings in the next section.

If several players fail at the same moment, work through the server settings below as well as the player steps.

Check prevent-proxy-connections

The Config Editor does not list this setting, so check it in the file:

1. Open the File Manager and open server.properties.
2. Look for prevent-proxy-connections. The default is false.
3. If it says true, change it to false, click Save and restart the server from the Console tab.

With it on, the server sends the player's IP address to Mojang, and players whose internet provider differs from the one Mojang has on record are kicked. Switching it off is a quick way to rule it out.

Players without a Java account

Bedrock players usually have no Java account. Use the Crossplay tab for them. After you enable crossplay, the Sign-in list under Bedrock settings offers Floodgate (no Java account), which lets Bedrock players join without a Java account. The tab installs Floodgate on Fabric and NeoForge. On Quilt it fetches the Fabric build, because Floodgate has no Quilt build on Modrinth. On Paper and Purpur, add the floodgate-spigot jar yourself first. Forge has no Floodgate build, so Bedrock sign-in through Floodgate is not available there. Let Bedrock players join your Java server has the full steps.

Turning online mode off

The setting is in the Config Editor: under Players, switch Online mode off, click Save changes, then restart the server. Two things change when you do:

• Players are no longer identified by their Mojang account. The server builds an ID from the name they type, so each player gets a different ID from the one they had before. Player data is stored per ID, so returning players can start with an empty inventory, and entries in the operator and whitelist files, which record IDs, can stop matching the same people.
• A player on a licensed account can still join, but so can everyone else.

To put things back, switch Online mode on again, save and restart.