Information

Full output of /ess version:
Server version: 1.15.1-R0.1-SNAPSHOT git-Paper-32 (MC: 1.15.1)
EssentialsX version: 2.17.1.34
LuckPerms version: 4.4.1
PlaceholderAPI version: 2.10.4
Vault version: 1.7.2-b107
EssentialsXSpawn version: 2.17.1.34

Server log: https://pastebin.com/NT8zrV9L

EssentialsX config https://pastebin.com/2yQeanmA

Help request

Problem
Server crash when a player quit the server, I believe by reading the error that Essentials had a problem saving in userdata file

What I have tried
I have searched in forusm yet haven't found anything or any solution, except something related to chmod but my linux knowledge is limited

Screenshots

Watchdog dumps stack traces regardless of whether a plugin caused it or not when the server has been lagging or unresponsive for a certain period of time.

Most likely this is not a problem with Essentials but with your server. If you only received this error once, I would not worry. If you crash consistently with the same stack trace pointing to com.earth2me.essentials.EssentialsConf.delayedSave then there may be an actual issue. Still, it may be worth checking timings and looking for other sources of lag that may have caused your server to crash.

Aight thank you for the response, it has been the first time so if it happens again pointing to delayedSave I'll make sure to reply.

Cleaning up for now, but if you do find further evidence on this feel free to respond and we can consider re-opening the issue.