What behaviour is observed:

Cannot join minecraft server, PlayerDisconnected message appears.

What behaviour is expected:

Log in to the minecraft server

Steps/models to reproduce:

Install SpongePls and ChangeSkin on Bungeecord, and use MySQL as the server
Install ChangeSkin on SpongeForge and setup sponge for bungeecord ip forwarding
Both BungeeCord and the Sponge server are in offline mode.
Attempt to connect to the spongeforge server via bungeecord.

Plugin list:

Minecraft, Minecraft Coder Pack, SpongeAPI, SpongeForge, BungeeTabListPlus-SpongeBridge, ChangeSkin, FlexibleLogin, GriefPrevention, KaroglanSignEditor, LuckPerms, MMCRestrict, Market, Nucleus, PlaceholderAPI, PlayerShopsRPG, ProjectCore, ProjectWorlds, Total Economy, UltimateChat, WorldEdit

Environment description

MySQL
Bungeecord build #1305

Plugin version or build number (don't write latest or the build number with #):

3.1

Error Log:

Hastebin / Gist link of the error or stacktrace (if any)
https://pastebin.com/PrStSdcZ

Configuration:

Hastebin / Gist link of your config.yml file
https://pastebin.com/LAPRFfet

What message does the client see?

And please post the complete version next time. The commit id is missing.

What version of SpongeForge do you use?

I forgot to mention - removing the ChangeSkin plugin from the bungeecord plugins directory completely fixes the problem, so I think it's probably something to do with ChangeSkin

BTW don't write #Number It's used to link to other tickets.

This disconnected shows up if there is something wrong during login process. Could you check the forge server log for any errors?

It could be a combination of SpongePls with mods and ChangeSkin.

This is all I could find in the forge log that's relevant to changeskin:
https://pastebin.com/idNV7Hr2

I think the problem is that I'm using mysql for bungeecord, but mariadb for sponge. Is there a way to use the same type for both bungeecord and sponge?

Also, the same thing happens even if I disabled SpongePls, so I doubt it's SpongePls.

Do you also enabled bungeecord support inside the Sponge global config (not only ip forwarding)?

Yes I have

bungeecord {
# If 'true', allows BungeeCord to forward IP address, UUID, and Game Profile to this server.
ip-forwarding=true
}

spongeforge-1.12.2-2611-7.1.0-BETA-2977
changeskin.sponge-3.1-3882ba3 100 (23-Mar-2018 12:07:54)
bungeecord 1​30​5 15-Mar-2018 09:47

I hope that's the complete version.

Oh and here's the message that the client sees:

And finally, here's the full log of bungeecord (nothing appears on the actual server, because the player never gets that far): https://pastebin.com/sZ8yB8cX

I removed the IP addresses from the bungeecord log.

And this?

    modules {
        [...]
        bungeecord=true
        [...]
    }

Oops, didn't realize there were two options for bungeecord.

It was false for me, but setting it to true fixed everything for me. It was an error on my part.

Thanks for the help!