Even though Minecraft has been out of beta testing since a while, it can still have glitches from time to time. When you merge it with an external server wrapper such as CraftBukkit, Tekkit and third-party plugins, most will eventually run into problems such as crashes, lag, errors and faulty plugins at some point. Server problems are usually unavoidable with most Minecraft servers and the more plugins and the larger your world, the more likely you are to have these issues. This guide will provide detailed information on how to troubleshoot a Minecraft server to help you find the root cause.
One point we (GGServers) would like to make is that server crashes and [most] causes of lag have nothing to do with the host themselves (this goes for any hosting company). Every host runs the Minecraft/External Minecraft server software (which is a .jar file) through Java, which is cross-platform (Windows, Mac & Linux Compatible). This allows all servers the ability to function on different OSes. Due to this, it isn't the host that is actually starting/running your server, it is the Minecraft/External Minecraft server software that is running through Java that is the brain of everything, the only time a crash is an issue on the host's side is if their actual physical hardware breaks down or if the operating system crashes. All other crashes are caused directly by Minecraft/External Minecraft server software and plugins themselves.
You will also want to understand that host companys cannot fix all Minecraft related problems for you as we did not program the game, CraftBukkit, Tekkit or the plugins you use - we can only give you our best effort at debugging the problems using our experience. User error is also something that is difficult for a host to fix since we did not configure your server nor did we install the plugins (exception being if you ordered the Plugin and Modpack Support addon), so you always want to provide as much detailed information as possible of how the problems started if you need help on these types of issues/problems. However, some problems may not be able to be resolved WITHOUT doing a whole reset/rollback. This is unfortunately the nature of Minecraft and the plugins that are based on it.
FIRST STEP IN ANY SERVER ISSUES
You, the server owner, must first check your console and server.log files (via FTP or built in file viewer). The console is a live version of the server.log (a txt-based file), but the server.log has a longer history because it contains all console log output. The console display is limited to the last few lines. Although some messages may seem unusual or cryptic within the console/server.log file, you will often find the error messages containing the name of the plugins that the error is related. An error message is preceded by a tag like, or similar to "[SEVERE]". Some errors will indicate the exact problem. This makes it easier for the server owner to correct the problem. Sometimes, however, the server.log file size can reach gigabytes (1000MB+), making it difficult to open. Usually, a server.log file that is larger than 1GB is due to chunk errors.
Tip: Delete your server.log file without the server running to make it easier to see startup/shut down errors. It wouldn't be enjoyable to have to download 100MB log files every time. If you want to keep it, you can rename the file to another name (example server.logOLD1).
Once you have identified the problem, the next step will be to ensure that all plugins installed are up to date (including your Minecraft/External Minecraft JAR). You can do this by clicking on the Multicraft panel's update button. This should clear up most, next to all plugin related errors, but if you are still getting errors after updating your plugins, then they can be related to other issues, which will require further investigation.
REMOVING WORLD AS A SOURCE TO THE PROBLEM
Sometimes, the problem is something within the world itself. To test this, go into your multicraft panel and change "level-name", which defaults to "world") to something other ("world2"), then hit "Save" and let the server restart automatically. This will create a new world folder in your server's directory called "world2" (Or other names if you chose a different name) and will be a plain, automatically generated, no user-input world. If you see the same errors in your server.log, please check again. NOTE: Changing the level-name could cause multi-world plugins to not work properly. If this happens, you may have to delete the newly created world from the multiworld plugins config file. Otherwise, the world will automatically be created again.
If this solves the problem on your server, it is likely that there is something wrong with your world file. This could include, but isn't limited to, water and redstone, lava large quantities of mobs or non-removal drop items. You can also check to determine if your plugins continue throwing errors in the server.log file.
You can change the name of the world to match your old one by simply changing the capitalization and spaces.
BASICS TO FIX PLUGIN PROBLEMS
Plugin errors are most often caused by incorrectly installed plugins (e.g., some plugins require that other plugins be installed in order to work). It is important to ensure that your Minecraft/External Minecraft server files are always up-to-date (from the game panel) and that all plugins you install support the exact same Minecraft server software version. Differences in these versions/different types of server software can cause errors, lag, and crashes. It is better to avoid installing plugins that do not support CraftBukkit. Plugins can sometimes be updated frequently, so you will always want to check on http://plugins.bukkit.org for the latest versions of your plugins.
If updating does not resolve the errors, it is likely that your config file is having issues. Some plugins require things such as a MySQL database (which GGServers can provide by request), and if you don't enter in your MySQL database login info, then the plugin will throw errors. Other problems with plugin configs may be caused by outdated config files. You will need to delete the config and restart the server to have the plugin generate a new file.
Some plugins also have data files that can become unusuable, in some cases, the data files can be manually edited to fix the problem, but you may end up having to remove (or rename) the entire data folder for the plugin to fix the issue. Many causes of errors outputting from configs is in the .yml files (config files extensions are .yml). Those files have a very, very specific format that you must adhere to no matter what. Failure to follow this format, even if it is a simple capitalization error, can render the plugin and any associated plugins inoperable. You can check the syntax of any .yml file using this site: http://yaml-online-parser.appspot.com/
TYPES OF PLUGINS THAT CAN CAUSE LAG:
The following plugins are some (but not limited to) that can cause server lag:
-Anti X Ray (or any xray-related plugin) – World Edit –NPC -Anti-cheat –Wrong version anti-lag plug-ins –Outdated/wrong versions of plugins in general
PROCESS OF LIMITATION:
Disabling plugins in groups is a great way of testing for server errors. This allows you to quickly narrow down the problem and speed up the process. This is simple, a good way to do this is to append .disabled onto the plugin file name, (example) worldedit.jar.disabled. If you are ready to re-enable your plugin(s), simply remove the.disabled tag from your plugin(s) then restart the server.
WHAT TO DO If YOUR SERVER DOES NOT START UP
There are a few causes of why a server won't start up (at all), so we'll go over a few here.
1. If you are running out of disk space, check your multicraft profile page to see if it has been reached. This is common if backup plugins are not kept track of. It creates hundreds of backups and takes up all your disk space. Remove anything you don’t use.
2. You have chunk errors. Chunk Errors spam error messages into your server.log file and makes it max out your disk space. The server.log file contains all error messages and can grow to gigabytes in size. In this situation, you will need the server.log file to be deleted and a new world to be created.
minecraft servers
3. Your Minecraft server JAR file has been corrupted or is not usable. You can upload the most recent version by using the update button within your multi-craft panel.
4. A plugin can stop/crashe the server upon startup. To fix this, please read the article 'The process for elimination'.
TYPES OF LAGA:
There are many types and meanings of lag. We'll cover a few of them here:
1. Movement lag, delayed block breaking and movement lag are two examples of a delay in block breaking. (This is also known under the name "rubber banding" and damage delays. This type of lag may be caused by network lag (on the clients or the hosts), lag on their own internet connection, server performance issues and plugin/world issues.
A plugin called "LagMeter", or another similar plugin, can be used to determine if lag is coming out of your world/plugins. You can also use the /lag command if you feel lag. If the TPS is close to 20, it could be a problem with other things.
2. Framerate issues on client side - Simply can't (or hardly). -- This type of lag is usually caused by something wrong with the servers chunk generation. TNT explosions or damage to chunks can also cause lag. If the lag lasts for more than 10 minutes, or continues after logging back into the server, a new universe may be necessary. This type lag can also be caused when plugins are used that have anti xray and ore obfuscation. You can either update or remove the plugin to resolve this issue. Many servers have disabled TNT altogether (not recommended for faction-based servers).
CONCLUSION
If you are experiencing some form of error or lag on your server and are unable to determine using this article, please feel free to open a ticket with our Technical Support team at: https://ggservers.com/billing/submitticket.php. To have your issue resolved quickly, please provide as many details as possible. Without detailed information on the issue, or on troubleshooting you may have already done, our tech support team would start from the most basic troubleshooting procedures and may be repeating what you have already completed.