Common Minecraft Error Fixes

Current Minecraft versions are very stable and easy to work with, even more so if you are only playing single-player games.

However, that doesn’t mean that problems and issues don’t happen when trying to play Minecraft, especially with friends using a server.

Before we get into specific errors, what causes them, and possible fixes, let’s talk about some things you can do and check before playing Minecraft in order to have a smooth experience, as well as, good practice for protecting video game files.

First and foremost when downloading and installing Minecraft look for incompatible software for the game. A list of all known incompatible hardware and the workaround can be found here.

A number of different antiviruses including the popular AVG Antivirus can interfere with the game in multiple ways and can make it hard for you to play with your friends or in some cases even start the game.

I personally use a combination of Malwarebytes which is the recommended antivirus software for the Minecraft players and Windows Defender that comes with a native Windows Install.

When playing any game it is important to back up your saved files and even your installation files. I always try to keep a separate folder for every game that I play regularly. This folder will contain any information I deem important for the game.

In Minecraft, I simply like to back up my saves and occasionally my mods if I enjoy a specific mod list. Always backup any files you aren’t okay with losing, if you want to go a step further you can back up these files to an external source, such as a thumb drive or portable hard drive/SSD.

Runtime Errors


Runtime errors are errors that occur while a program is running, for example, if you are actively playing Minecraft or trying to start Minecraft you may encounter a runtime error.

There are different types of runtime errors, one is a logic error which means that the program produced the wrong output, memory leaks are another very common runtime, and lastly, the most noticeable runtime error is when a program crashes to the desktop. Here are three common Minecraft runtime errors and how you can fix them. or

If you receive this error it is likely that your Minecraft world is corrupted or there is an invalid SJONT/NBT formatting in your save files.

This happens because Minecraft uses an external package to parse all the JSON formatting. There are two ways to fix this issue. One is to simply restore your save file from backup; another more complicated solution is to search through your save files for the malformed setting. I personally would just restore my save file.


This error is pretty basic and very easy to fix, it is also more likely to occur when playing with large mod packs as they require a lot more power than vanilla Minecraft. To fix this error allocate more ram to the mod pack. This can typically be done using the launcher settings.

I suggest allocating a minimum of 4gigs to the mod pack, some packs I’ll even allocate up to 8gigs of ram. Remember that you can only allocate what you have on your computer and your computer hardware will limit what you can play.

If you only have 4gigs of ram in your computer only allocate 3 because your computer will need ram to run other processes. With that said remember to close out any applications that you don’t need open while playing Minecraft.

RuntimeException: No OpenGL context found in the current thread Or org.lwjgl.LWJGLException: Pixel format not accelerated

This error means that your graphics card or driver cannot handle Minecraft. This problem may be because you need to update your graphics card drivers or you may have the default drivers that don’t support OpenGL.

Simply update your graphics cards through the manufacturer’s software or install the manufacturer’s drivers that do support OpenGL. If that does not fix the problem then you may need to purchase a newer graphics card.

Multiplayer Errors

minecraft multiplayer errors

Multiplayer errors are much more common than say runtime errors or even crash errors. This is because running a server for multiple people to log onto and play together is generally more complicated than just launching a single-player game.

Running a Minecraft server successfully is contingent on multiple things including a good internet connection, storage space, and ram space.

Connection refused: connect

This happens because the server that you are trying to access is not online or the IP address entered into the port is wrong. This can also happen if an entire server goes down. To fix this issue confirm that the address for the server is correct and configured properly. You can also try restarting the server and checking for errors if you have access to it.

End of stream

This typically means that the server has stopped sending information back to the client aka your computer. This can be fixed by restarting Minecraft, restarting the server if you have access to it, and checking that both your computer and the server has a good internet connection.

If you do not have access to the server contact the server owners to let them know the problem.

Failed to login: Bad Login

This can occur when you attempt to log in quickly after your last login attempt or when you are trying to connect a non-vanilla client to a vanilla server or vice versa.

To fix this confirm that you are running the same version and mod pack as the server you are attempting to connect to. You should also run a speed test to make sure your ping latency isn’t too high. You can do this at

Failed to login: the authentication servers are currently down for maintenance

This typically means that the server can’t contact the authentication server to verify the identity of the player. In other words, the authentication server for Minecraft is down.

There is not much you can do but wait for the server to come back up. You can also check to make sure your firewall isn’t being blocked, however, this is unlikely.

Failed to login: invalid IP

This means that Mojang servers can’t validate your IP address because something is wrong on their end. Try logging in again at a later time and check to see if there are any reported server outages from Mojang. Server returned HTTP response code: 503

minecraft game

This means that is down so it can’t authenticate your identity. Simply wait for to come back up, if the problem persists and you don’t think it is on’s end contact the server owner and let them know what is going on. Connection reset

There are multiple reasons for this error including the server shutting down or doing something intensive, an internet connection issue.

This is occasionally returned when a server is in the process of shutting down or starting up, this most often happens during nightly backups. Try logging in again in 15 or so minutes. If the problem persists contact the server owner.

Internal Exception: io.netty.handler.timeout.ReadTimeoutException

This means that your game can’t keep up with the server or doesn’t have enough processing power and you are falling out of sync with the server.

You can try to close any programs that might be bogging down your computer and internet connection. If this does not work you may need to invest in faster internet service and a faster computer.

Outdated client!

This happens when you are trying to connect to a server that is running a newer version of Minecraft than you are. You need to change your Minecraft version to the version that the server is running.

Outdated server!

This is basically the opposite of an outdated client error. It means that the server you are trying to connect to is using an older version of Minecraft than you are. You just need to change to the same version of Minecraft as the server you are trying to connect to.

This server responded with an invalid server key

This is technically a stop measure that is supposed to help with exploiting modified servers but there is a bug that tends to throw false positives. Simply log in again to clear this error.

Took too long to log in

This means that is down or having a problem so they can’t authenticate who you are. Trying logging in again at a later time. If the problem persists contact the server owner or admin to explain what is going on.

User Not Premium

This happens when you are running a hacked or torrent version of Minecraft. You can’t play multiplayer games with people unless you buy a legal copy of the game.

You are not whitelisted on this server

This happens when the server admin or owner is not allowing you access to the server. Unless you have been invited then you likely can’t just access any server and play. This is to keep random people from joining the game and ruining it for others. Contact the server owner or an admin and talk to them about getting whitelisted for the server.

Crash Errors

Crash errors happen while playing the game and cause the game to completely crash. In many cases accessing the crash log and having someone with experience troubleshooting the game look it over will help solve the problem. Here are a couple of common crash errors.

Failed to check session lock, aborting

This means that there is most likely a lock on part of the world, for example, the terrain or a saved element, such as a player or chest. If you are an admin delete the session.lock in the world save folder, otherwise, contact the owner or admin to get this problem fixed.


This happens when Minecraft crashes on startup. To fix this I recommend pulling your crash log and uploading it to a Minecraft support forum and have someone look it over.

Minecraft Support

minecraft support center

Here is a list of resources you can use to find help and solutions to errors that happen in the game.

  • The Minecraft help corner is the one-stop-shop for issues related to all versions of Minecraft. You can pursue here to find other common issues and issues related to other versions of Minecraft.
  • Minecraft wiki has various articles and answers for a variety of questions related to Minecraft.
  • The Minecraft Bug tracker lets you submit bugs and view current issues. This is really helpful if you are encountering an error that doesn’t have an obvious answer.
  • The community discord is a collection of players and offers people the ability to get community help easily. Simply click the link and enter a nickname to join. You can also download the Discord client to keep up from your desktop.
  • Twitter is a great way to get support for various websites, software, and video games. Many developers Mojang included often announce various server level activities, such as, maintenance, downtime, and other game interruptions.


Question: HELP! My error isn’t on this list?

Answer: Look through the resources for help in the last section of the article. You can also try posting your issue in the community and getting some direct help.

Question: Why does anti-virus mess with Minecraft?

Answer: Most anti-viruses set firewall rules and other limitations in order to protect you from accessing potentially harmful things on the internet. Unfortunately, this often messes with the ports needed for Minecraft and other multiplayer games to run. Additionally, many antiviruses are extremely resource-intensive and can really bog down a computer’s ability to run well. Choose your antivirus wisely and don’t go with what they suggest at the store.

Question: Why can’t I play online with a torrent version of Minecraft?

Answer: In order to be registered to the authentication server, you need to buy a copy of the game through Mojang and create an account. Without a legal copy of the game, you can’t be registered to Mojang’s authentication server.

Question: I don’t understand what this crash log says?

Answer: Don’t worry crash logs are in a completely foreign language to me too and I have an IT degree. I strongly suggest posting your crash long on a Minecraft forum or asking for help through discord.

The people that frequent these support forums tend to have a lot of practice reading and understanding logs and are happy to help you figure out what is wrong.

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