Hi! I will install CoreProtect for the easier rollbacks, and when I try for install, I type the command "/co" didn't works, but it don't say "Unknown command. Try /help for a list of commands" I tried to update my Java version server (PloudOS) but I can't join with java 16, so I go to java 8 and it correctly join. If you can help I will thank you so much, thanks for listening me!

Sorry if you didn't understand the issue, im Spanish and my English level is so low

Please provide a copy of your startup log.

[CoreProtect] Enabling CoreProtect v19.0
[06:24:52 INFO]: [CoreProtect] Spigot 1.16 or higher is required.
[06:24:52 INFO]: [CoreProtect] CoreProtect was unable to start.
[06:24:52 INFO]: [CoreProtect] Disabling CoreProtect v19.0
[06:24:52 INFO]: [CoreProtect] Finishing up data logging. Please wait...
[06:24:52 INFO]: [CoreProtect] Success! Disabled CoreProtect v19.0

I need to change the Minecraft version? (Actually, 1.8.8) Or the plugin version?

If using MC 1.8.8, you'll need to use a version of CoreProtect for MC 1.8, and reset your database (e.g. delete the database.db file)

https://www.coreprotect.net/legacy-edition