System properties

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

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

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.

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 the io_uring support and Epoll. If set to true, Velocity will use Java’s NIO transport instead.

velocity.disable-iouring-transport

• default: false
• description: Whether to disable Netty’s io_uring transport method. If set to true, Velocity will use Netty’s Epoll transport instead. This setting is overridden if velocity.disable-native-transport is set to false.

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 and removed in 1.21.2 to help modded servers transition to this change.

List of environment variables

VELOCITY_FORWARDING_SECRET

• default: unset
• description: Overrides the forwarding secret inside the forwarding-secret-file.