Information

Full output of /ess version:

Server version: 1.14.4-R0.1-SNAPSHOT git-Paper-137 (MC: 1.14.4)
EssentialsX version: 2.17.0.5
Vault version: 1.7.2-b107

XLRewards-2.2.6 is also installed

Server log: https://gist.github.com/Whist34/49f0a760a1282308cddbd8eb164123c5

EssentialsX config: https://gist.github.com/Whist34/bef5b12a24aa53eb653eaa269d279e15

Details

Description
XLRewards provides ability to claim rewards through an ingame gui. You open the gui click on the reward to claim.
This reward is time based and gives you xp.
I have already discussed the issue with the author of XLRewards and after testing found that the error occurs even when XLRewards is not installed.
Issuing the command: "/xp add Dhenier 30000" results in an EssentialsX error with the result that the player does not receive any experience.

More info: I am in the process of adding Essentials to an existing server. On the existing server this command works as intended without EssentialsX installed.
Xp command as described on the Minecraft Wiki: https://minecraft.gamepedia.com/Commands/experience

Steps to reproduce
Login.
Console issues command: /xp add 300
Error -> No experience

Expected behavior
Login.
Console issues command: /xp add 300
Player receives experience

Screenshots
I have screenshots of the XLRewards GUI interface, but I do not think they are necessary because all of the debug information is included in the server log.
Please let me know if you want me to add those.

After more testing I have found if I use "/experience add Dhenier 300" Then the player receives the experience. But shouldn't the xp command still work? Or would it need to be a command like minecraft:xp?

Essentials overrides a lot of the default vanilla commands. /xp add ... is not an Essentials subcommand, and so its default behaviour is to display the XP statistics of the first argument - it tries to search for a player named add, which of course, doesn't exist.

If you wish to continue using the /xp command as in vanilla, then you need to use /minecraft:xp to explicitly specify that you want the game to use the vanilla command. Otherwise, you can switch your command usage to the Essentials syntax, which in this case is /xp give <player> <amount>.

You can refer to this page for all Essentials commands and command syntax.

I changed to using /experience as the command. I'm going to close this issue. Thanks for the help.