Yea I know I don't have a SSL certificate, but something odd is causing the server to instantly shut down the moment the web socket is enabled:

[14:27:24] [Server thread/INFO]: [JPanel] Enabling JPanel v1.0-SNAPSHOT
[14:27:28] [Server thread/WARN]: SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
[14:27:28] [Server thread/WARN]: SLF4J: Defaulting to no-operation (NOP) logger implementation
[14:27:28] [Server thread/WARN]: SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
[14:27:28] [Server thread/INFO]: [JPanel] JPanel enabled!
[14:27:28] [Server thread/INFO]: [BKCommonLib] Enabling BKCommonLib v1.70-SNAPSHOT
[14:27:28] [Server thread/INFO]: [BKCommonLib] BKCommonLib is running on Spigot (git-Paper-854) : v1_10_R1 (Minecraft 1.10.2)
[14:27:28] [Server thread/INFO]: [BKCommonLib] [Network] Now using the ProtocolLib library to provide Packet Listener and Monitor support
[14:27:28] [Server thread/INFO]: [BKCommonLib] Not enough wrappers. Needs more wrappers. Moooreee...
[14:27:28] [Server thread/INFO]: BKCommonLib version 1.70-SNAPSHOT enabled! (0.099s)
[14:27:28] [Server thread/INFO]: [mcMMO] Enabling mcMMO v1.5.07-SNAPSHOT-b${BUILD_NUMBER}
[14:27:28] [Thread-9/INFO]: [JPanel] WebSocket started
[14:27:28] [Thread-4/INFO]: Stopping server

@MuhsinunCool no it isn't, unless your issue also involves enabling SSL, and the server stopping the moment the websocket is started.

Here's my issue with the starting sequence; dunno if it's related or not:
[17:18:19] [Server thread/INFO]: [JPanel] Enabling JPanel v1.0-SNAPSHOT [17:18:19] [Server thread/WARN]: log4j:WARN No appenders could be found for logger (spark.staticfiles.StaticFilesConfiguration). [17:18:19] [Server thread/WARN]: log4j:WARN Please initialize the log4j system properly. [17:18:19] [Server thread/INFO]: [JPanel] JPanel enabled!

@RoboMWM Just thot that since urs sed this:
[14:27:28] [Server thread/WARN]: SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder". [14:27:28] [Server thread/WARN]: SLF4J: Defaulting to no-operation (NOP) logger implementation [14:27:28] [Server thread/WARN]: SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.
and so did mine, I just thot that they might've been related idk :)

Not related, I get that regardless of the SSL setting I use.

Have you followed the instructions for using https?

From the bukkitdev page:

HTTPS support

In the latest beta (Beta 6) I've added standalone https support! This requires some configuration.

1. First, you'll need to put a keystore file in the JPanel folder. You can either attempt to generate one using these instructions or download a premade keystore file from here. The pre-made keystore has an unsigned certificate that'll get you going with security warnings in most browsers, so isn't recommended unless you can't use an actual certificate.

2. Stop the server, and enter the name of the keystore file (with file extension) under keystore-name and the password for the keystore file under keystore-password in the JPanel config.yml. If you're using the premade keystore, use the password 'password' (ultra secure).

3. Restart the server, then access the panel normally except with https.

JPanel is also causing the server to stop when it's reloaded. Seeing that the message comes from another thread (not the main thread), my guess is that jetty or whatever is calling a System#exit or similar?

No idea what you're talking about here. What plugin limit restriction are you talking about? Where is this hardcoded into the plugin? (I did searches for "shutdown" with no results in github search).

Also, not saying it's the root cause, but setting SSL to true without having a cert setup does cause the plugin (or whatever library) to shutdown the server.

I guess @rymate1234 removed the Bukkit#shutdown call in onDisable in a recent commit, but once upon a time it was there and that's what I was referring to. ploader-bypass-plugin-limit-restrictions.56669/

He does have stop() (or did, idk rn), but I never saw shutdown(). Would you know what version had it? Because there was no shutdown() existing in the codebase last year

No idea what that plugin is for other than allowing you to blacklist plugins that should not be reloaded when running a server reload. I do not use /reload but an arguably even eviler /plugman reload :p

Also I should add that this has nothing to do with reloading the plugin, nor is the shutdown method called from the main thread given the provided log.