Reminder: this version requires Java 17, ensure you update Java as the latest works with old versions, even 1.8. If you want to get larger updates early consider becoming a supporter https://viaversion.com/donate.

Changelog:

• 1.21 support (by KennyTV / EnZaXD / RK_01)
• Sponge / Bungee support is now provided through ViaBungee/ViaSponge.
• Various API changes (by KennyTV)
• Added handle-invalid-item-count config option to gracefully handle items with invalid stack sizes in 1.20.3->1.20.5 (by EnZaXD)
• Added viaversion player <*/playername> subcommand to view protocol info of a specific player (by EnZaXD)
• Ignore invalid chunk entities in 1.20.3->1.20.5 (by KennyTV)
• Fixed issues with thrown projectiles for 1.20.5 clients on 1.19 servers and older (by KennyTV)
• Fixed various issues due to missing tags (by RK_01)
• Fixed various block entity tags in 1.20.3->1.20.5 (by EnZaXD)
• Fixed conversion of firework tags without explosions in 1.20.3->120.5 (by EnZaXD)
• Fixed positionless lodestone tracker conversion (by EnZaXD and Pantera07)
• Fixed painting items with specific variant tags in 1.20.3->1.20.5 (by KennyTV)
• Fixed villager trade handling when they contain empty items in 1.20.3->1.20.5 (by KennyTV)
• Fixed various issues in show_item conversion in 1.20.3->1.20.5 (by EnZaXD)
• Fixed items with custom names not being italic sometimes in 1.12.2->1.13 (by EnZaXD)
• Changed logs/warnings to include the relevant version (by EnZaXD)
• Fixed book signing in 1.8->1.9 (by EnZaXD)
• Fixed block place sounds playing twice in 1.8->1.9 (by EnZaXD)
• Small fixes to edge cases in data parsing in various versions (by EnZaXD)
• Backup negative item amounts in 1.10->1.11 for creative mode clients (by EnZaXD)
• Changed viaversion displayleaks subcommand to be able to set detection level (by EnZaXD)

Huge thanks to Kenny, EnZaXD, RK_01 for contributing towards this release.