Update the Via plugin family as a tested release set

ViaBackwards and ViaRewind depend on the Via translation chain. Updating one library while retaining an incompatible companion can fail at startup or break only the oldest client. Treat the installed family as a tested set, while keeping server and Java compatibility in view.
Record the starting point
Record all Via plugin filenames and release numbers, the server platform, Java runtime and advertised client range. Download releases from their maintainers. Preserve the current JARs and configuration outside the active plugins directory; duplicate JARs in that directory can make loading ambiguous.
Work through the change
Read the release requirements for the target ViaVersion, ViaBackwards and ViaRewind builds. Include only components your client range needs and check support for the server platform.
Stop the server normally, replace the selected artifacts and retain existing configuration unless the release notes require a documented migration. Do not use a plugin hot-loader for the update.
Start and read the first dependency or startup error before testing players. Resolve a failed companion load rather than continuing because the main server reached its ready message.
Test a native client, a newer translated client and the oldest client you advertise. Exercise inventory movement, world travel and a representative menu rather than checking the server list alone.
Check the result
Every required component should report a successful load, and each test client should complete the same small gameplay checklist. Save the final release combination with the test date. This gives staff a known working baseline when the next Minecraft client update arrives.
If the result differs
A missing class or incompatible API error after replacement usually deserves a dependency comparison before configuration changes. If one client fails, confirm its protocol direction is supported by the installed chain. A development snapshot may not provide the same support as a stable release.
Stop and restore the previous matching set if a required client regresses. Retain the failed startup log and new artifact names for reporting. Do not downgrade the world or delete player data as a workaround for an incompatible translation library.
Use the file manager for the specific configuration file described in this guide; the screenshot shows the panel, not a plugin interface.
References and related help
ViaVersion maintainer reference 1
ViaVersion maintainer reference 2
ViaVersion maintainer reference 3
Allow compatible Minecraft Java clients with ViaVersion
Back up game files before making changes