While our Tech Support staff are available 24/7 to help you with problems on your server, you might feel like getting your hands dirty yourself - here you'll find links to known bugs and common problems relating to Minecraft servers, so that if you are experiencing a problem, you can check here for help diagnosing and fixing that problem.
You can see a list of common errors at our Category:Errors page.
When your Minecraft server starts up, it creates one or more log files. While the server is running, everything important that happens on the server is written to these log files. They provide a handy reference to what's going on on your server - player log-ins, mod and plugin messages, server chat and, importantly, error messages.
You can access your log files through SFTP. Use the 'minecraft' username to log in over SFTP - you'll connect to your /home/minecraft directory, and you'll see your log files there. There maybe one, or several - the most important ones are screen.log, server.log and, if you're running a Forge server, forge.log (the Forge log is the first log to check for errors if you're running a Forge server).
When reading your logs, look for obvious errors and spam messages. It can be difficult to know what to look for, but error messages usually have the word 'error' in there somewhere, and a 'Caused By' section. Once you get familiar with checking logs, you'll find these errors become more obvious. Spam messages are any system messages (not player chat messages) that repeat frequently; these indicate that something, like a mod or plugin, is too busy or having difficulty, and this can cause lag on your server.
[Server thread/DEBUG] [FML/]: Gathering id map for writing to world save world
[Server thread/DEBUG] [OpenMods/]: openblocks.common.MapDataManager
$MapDataResponseEvent.writeToStream(MapDataManager.java:85): Trying to propagate invalid map data 0
World may have leaked; seen xxx times
Generating apatite vein at xxx -xxx
[Server thread/DEBUG] [enetbridge/]: Detected new dirs for thermalexpansion.block.cell.TileCell@393ec73: , [DOWN, NORTH].
[ForgeModLoader] Ars Magica 2 >> Saved 2 power node entries
[ForgeModLoader] Saved ModFlags.dat NBT data file successfully.
java.lang.RuntimeException: Failed to check session lock for world ./world/etc, aborting
From the crash report;
Description: Ticking entity