Complete reference
All Minecraft Error Codes
30 error codes — find the code you're seeing and jump straight to the fix. Each entry links to a full step-by-step guide.
2 server-side·11 client-side·11 mixed
| Code | Meaning | Cause | Fix |
|---|---|---|---|
AUTHENTICATION-SERVER-DOWN | Minecraft could not reach Microsoft authentication services to sign in. | Server or client | Fix guide → |
CONNECTION-LOST | Minecraft lost connection to the server or realm mid-session. | Server or client | Fix guide → |
CONNECTION-RESET | The multiplayer server closed the TCP connection before join completed. | Server or client | Fix guide → |
COULD-NOT-CREATE-JVM | The Minecraft launcher could not initialize a Java Virtual Machine. This prevents the game from starting at all. Common causes are an invalid JVM argument, too much RAM allocated, or a corrupted Java installation. | Client-side | Fix guide → |
CRASH-REPORT | Minecraft's Java Virtual Machine (JVM) encountered a fatal error that could not be caught by the game. A crash-report or hs_err_pid log file was created containing the stack trace and error details. | Client-side | Fix guide → |
DISCONNECTED | Minecraft ended your multiplayer session with a generic disconnected message. | Server or client | Fix guide → |
END-OF-STREAM | The network connection to the Minecraft server closed unexpectedly. The stream of data ended before Minecraft expected it to. | Server or client | Fix guide → |
EXIT-CODE-0 | Minecraft's JVM exited cleanly (exit code 0 means normal termination), but the game closed unexpectedly from the launcher's perspective. This is often the launcher losing track of the process rather than a true crash. | Client-side | Fix guide → |
EXIT-CODE-1 | The Java Virtual Machine running Minecraft crashed and exited with code 1, indicating a fatal error. This is typically a Java or mod compatibility issue. | Fix guide → | |
EXIT-CODE-255 | Minecraft's Java process was terminated by the operating system or exited with an error code indicating an abnormal kill. This can result from an OS-level out-of-memory kill, a forced process termination, or a JVM internal error that caused an ungraceful exit. | Client-side | Fix guide → |
FAILED-TO-CONNECT | Minecraft Java or Bedrock could not reach the multiplayer server. | Server or client | Fix guide → |
FAILED-TO-DOWNLOAD | The Minecraft Launcher failed to download one or more game files needed to launch. The download was interrupted or a file was corrupted. | Server or client | Fix guide → |
FLYING-NOT-ENABLED | The server detected that your client was flying when flying is not permitted. The anti-cheat kicked you to prevent exploitation. | Fix guide → | |
INTERNAL-EXCEPTION | Minecraft encountered an unhandled network exception in its Netty I/O layer, causing a disconnect from the server. | Server or client | Fix guide → |
INVALID-SESSION | Minecraft rejected your login session — invalid or expired authentication. | Client-side | Fix guide → |
IO-NETTY | Minecraft lost connection with an io.netty network exception — often timeout or forced disconnect. | Server or client | Fix guide → |
JAVA-HEAP-SPACE | Minecraft ran out of allocated Java heap memory. The JVM cannot allocate more objects because all configured RAM is used. This causes an immediate crash. | Client-side | Fix guide → |
LOGIN-FAILED | Minecraft could not sign in to Microsoft account. | Server or client | Fix guide → |
LWJGL-ERROR | The LWJGL (Lightweight Java Game Library) that Minecraft uses for windowing and OpenGL context creation failed to initialize. This prevents Minecraft from creating a game window. | Client-side | Fix guide → |
MULTIPLAYER-DISABLED | Your Microsoft or Minecraft account does not have multiplayer enabled. A parental control or account setting is blocking online play. | Fix guide → | |
NOT-WHITELISTED | The Minecraft server has a whitelist enabled and your username is not on it. The server denied your connection. | Server-side | Fix guide → |
OPENGL-ERROR | Minecraft encountered an error in the OpenGL rendering pipeline. This can cause graphical corruption, a black screen, or a game crash. | Client-side | Fix guide → |
OUT-OF-MEMORY | Minecraft's Java process ran out of allocated memory (heap space). The game crashed because it could not allocate more RAM. | Fix guide → | |
OUTDATED-CLIENT | Your Minecraft client version is older than the multiplayer server. | Client-side | Fix guide → |
OUTDATED-SERVER | Your Minecraft client version does not match the multiplayer server version. | Client-side | Fix guide → |
PIXEL-FORMAT-NOT-ACCELERATED | Minecraft's OpenGL context failed because your GPU driver does not support the required OpenGL pixel format or is not hardware-accelerated. | Fix guide → | |
SERVER-FULL | The Minecraft server has reached its maximum player capacity. No new connections are accepted until a player leaves. | Server-side | Fix guide → |
SSL-EXCEPTION | Minecraft could not establish a secure connection to a server because the SSL/TLS handshake failed. This prevents joining online servers that require SSL verification. | Fix guide → | |
UNABLE-TO-ACCESS-JARFILE | The Minecraft launcher cannot find or read the game's .jar file. The launcher is pointing to a path that does not exist, was deleted, or has restricted permissions. | Client-side | Fix guide → |
UNABLE-TO-CONNECT-WORLD | Bedrock or Realms could not load your saved world or Realm. | Server or client | Fix guide → |
Mixed (Server or Client) — 11 codes
AUTHENTICATION-SERVER-DOWNMinecraft could not reach Microsoft authentication services to sign in.CONNECTION-LOSTMinecraft lost connection to the server or realm mid-session.CONNECTION-RESETThe multiplayer server closed the TCP connection before join completed.DISCONNECTEDMinecraft ended your multiplayer session with a generic disconnected message.END-OF-STREAMThe network connection to the Minecraft server closed unexpectedly. The stream of data ended before Minecraft expected it to.FAILED-TO-CONNECTMinecraft Java or Bedrock could not reach the multiplayer server.FAILED-TO-DOWNLOADThe Minecraft Launcher failed to download one or more game files needed to launch. The download was interrupted or a file was corrupted.INTERNAL-EXCEPTIONMinecraft encountered an unhandled network exception in its Netty I/O layer, causing a disconnect from the server.IO-NETTYMinecraft lost connection with an io.netty network exception — often timeout or forced disconnect.LOGIN-FAILEDMinecraft could not sign in to Microsoft account.UNABLE-TO-CONNECT-WORLDBedrock or Realms could not load your saved world or Realm.Server-side — 2 codes
Client-side — 11 codes
COULD-NOT-CREATE-JVMThe Minecraft launcher could not initialize a Java Virtual Machine. This prevents the game from starting at all. Common causes are an invalid JVM argument, too much RAM allocated, or a corrupted Java installation.CRASH-REPORTMinecraft's Java Virtual Machine (JVM) encountered a fatal error that could not be caught by the game. A crash-report or hs_err_pid log file was created containing the stack trace and error details.EXIT-CODE-0Minecraft's JVM exited cleanly (exit code 0 means normal termination), but the game closed unexpectedly from the launcher's perspective. This is often the launcher losing track of the process rather than a true crash.EXIT-CODE-255Minecraft's Java process was terminated by the operating system or exited with an error code indicating an abnormal kill. This can result from an OS-level out-of-memory kill, a forced process termination, or a JVM internal error that caused an ungraceful exit.INVALID-SESSIONMinecraft rejected your login session — invalid or expired authentication.JAVA-HEAP-SPACEMinecraft ran out of allocated Java heap memory. The JVM cannot allocate more objects because all configured RAM is used. This causes an immediate crash.LWJGL-ERRORThe LWJGL (Lightweight Java Game Library) that Minecraft uses for windowing and OpenGL context creation failed to initialize. This prevents Minecraft from creating a game window.OPENGL-ERRORMinecraft encountered an error in the OpenGL rendering pipeline. This can cause graphical corruption, a black screen, or a game crash.OUTDATED-CLIENTYour Minecraft client version is older than the multiplayer server.OUTDATED-SERVERYour Minecraft client version does not match the multiplayer server version.UNABLE-TO-ACCESS-JARFILEThe Minecraft launcher cannot find or read the game's .jar file. The launcher is pointing to a path that does not exist, was deleted, or has restricted permissions.