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Velocity System Properties

These system properties can be set when you start your server allowing for the configuration of various settings.

Danger Ahead

Setting flags for the JVM can alter how it operates and the same goes for the Velocity server. If you are unsure about what a flag does, it is recommended that you do not use it.

How they work​

System properties are set when you start your server. For example, if you are using a .bat or a .sh file to start your server, you can add the system properties to the file. For example:

java -Dvelocity.packet-decode-logging=true -jar velocity.jar
info

Some of Velocity's system properties contain a . character in their name. When using PowerShell, these will require wrapping in quotes. i.e. "-Dvelocity.packet-decode-logging=true"

Where a -D is used to set a system property, and the system property is velocity.packet-decode-logging with a value of true. Otherwise, just add them to the start command.

note

The default value shown may not be set for the property but will only be used by Velocity if it is not explicitly set.

List of system properties​

auth.forceSecureProfiles:​

  • default: true
  • description: Overrides force-key-authentication from the config. If not set, it will be automatically set to the current config value.

velocity.natives-tmpdir:​

  • default: unset
  • description: Temporary directory for Velocity native files. (If set, it will also define io.netty.native.workdir)

velocity.max-known-packs:​

  • default: 64
  • description: Limits known packs to the Vanilla default to prevent crashing Velocity.

velocity.max-packets-per-flush:​

  • default: 8192
  • description: The max amount of packets before the queue is flushed automatically.

velocity.log-server-backpressure:​

  • default: false
  • description: Whether Velocity should log if the server connection is writable and thus if the player connection will be auto-read.

velocity.packet-decode-logging:​

  • default: false
  • description: Whether packet decoding errors should be logged extensively.

velocity.increased-compression-cap:​

  • default: false
  • description: Whether the maximum uncompressed packet size should be set to its maximum supported limit (128 MiB) instead of the Vanilla limit (8 MiB).

velocity.disable-native-transport:​

  • default: false
  • description: Whether to disable Netty's native transport methods like Epoll. If set to true, Velocity will use Java's NIO transport instead.

velocity.natives-disabled:​

  • default: false
  • description: Whether native functionality for specific operating systems should be disabled.

velocity.strictErrorHandling:​

  • default: true
  • description: Whether the client should disconnect on packet errors. Temporarily added in MC 1.20.5 to help modded servers transition to this change.