What behaviour is observed:

Whenever someone logs in to the server, it generates the same error.

What behaviour is expected:

None

Steps/models to reproduce:

When a user logs in to the server.

Plugin list:

AuthMe, ChangeSkin, ChatInjector*, Chunkmaster, Citizens, CitizensCMD, CleanMotD*, Essentials, EssentialsChat, EssentialsSpawn, FarmLimiter, FogusCore, GoldenCrates, GUIPlus, Holograms, HologramsPlaceholders*, Jobs, LuckPerms, mcMMO, MIReplacer, MMOItems, MMOLib, Multiverse-Core, MythicMobs, PacketLimiter, Pingas*, PlaceholderAPI, ProtocolLib, QuantumShop, Shopkeepers, SuperbVote, TAB, Vault, VoteParty, Votifier, WorldEdit, WorldGuard

Environment description

Standalone server using MySQL

Plugin version:

3.1-SNAPSHOT-993142d

Error Log:

Hastebin / Gist link of the error (if any)
https://hastebin.com/cijagoguhu.sql

Configuration:

Hastebin / Gist link of your config.yml file
https://hastebin.com/omajejotih.makefile

You seemed to deleted the table ChangeSkin uses

That's what I'm thinking too. Is it possible to add the table manually?

Yes you could use this file creating it manually:

https://github.com/games647/ChangeSkin/blob/master/core/src/main/resources/create.sql