Starting minecraft server 1.20.1 craftbukkit. With the latest version of ProtocolLib and version 5.1.0 both have the same problem.
After the server gives "done" it displays an error:

[19:19:47] [Server thread/INFO]: Done (13.847s)! For help, type "help"
[19:19:48] [Server thread/INFO]: Error Cannot perform automatic updates. (java.lang.NullPointerException: Cannot invoke "com.comphenix.protocol.updater.Updater.isChecking()" because "this.updater" is null) occurred in ProtocolLib v5.1.0.
[19:19:48] [Server thread/ERROR]: [ProtocolLib] INTERNAL ERROR: Cannot perform automatic updates.
If this problem hasn't already been reported, please open a ticket
at https://github.com/dmulloy2/ProtocolLib/issues with the following data:
Stack Trace:
java.lang.NullPointerException: Cannot invoke "com.comphenix.protocol.updater.Updater.isChecking()" because "this.updater" is null
at com.comphenix.protocol.ProtocolLib.checkUpdates(ProtocolLib.java:540)
at com.comphenix.protocol.ProtocolLib.lambda$createPacketTask$0(ProtocolLib.java:511)
at org.bukkit.craftbukkit.v1_20_R1.scheduler.CraftTask.run(CraftTask.java:77)
at org.bukkit.craftbukkit.v1_20_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:414)
at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:1208)
at net.minecraft.server.dedicated.DedicatedServer.b(DedicatedServer.java:374)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:1155)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:980)
at net.minecraft.server.MinecraftServer.lambda$0(MinecraftServer.java:295)
at java.base/java.lang.Thread.run(Thread.java:833)
Dump:
manager:
com.comphenix.protocol.injector.PacketFilterManager@7b772d1d[
plugin=ProtocolLib v5.1.0
server=CraftServer{serverName=CraftBukkit,serverVersion=3871-Bukkit-3f9263b,minecraftVersion=1.20.1}
reporter=com.comphenix.protocol.ProtocolLib$1@3a6c93ee
minecraftVersion=(MC: 1.20.1)
asyncFilterManager=com.comphenix.protocol.async.AsyncFilterManager@5b42b486
pluginVerifier=com.comphenix.protocol.injector.PluginVerifier@199f6536
inboundListeners=com.comphenix.protocol.injector.SortedPacketListenerList@2d9290b3
outboundListeners=com.comphenix.protocol.injector.SortedPacketListenerList@733f950c
registeredListeners=[PacketAdapter[plugin=SuperVanish, sending=ListeningWhitelist[priority=HIGH, packets=[TAB_COMPLETE[class=PacketPlayOutTabComplete, id=15]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST], PacketAdapter[plugin=SuperVanish, sending=ListeningWhitelist[priority=NORMAL, packets=[SERVER_INFO[class=PacketStatusOutServerInfo, id=0]], gamephase=PLAYING, options=[]], receiving=EMPTY_WHITELIST]]
packetInjector=com.comphenix.protocol.injector.netty.manager.NetworkManagerPacketInjector@3d97e969
playerInjectionHandler=com.comphenix.protocol.injector.netty.manager.NetworkManagerPlayerInjector@5f439d38
networkManagerInjector=com.comphenix.protocol.injector.netty.manager.NetworkManagerInjector@666d996b
debug=false
closed=false
injected=true
]
Sender:
com.comphenix.protocol.ProtocolLib@6b2b87a9[
statistics=com.comphenix.protocol.metrics.Statistics@28426da9
packetTask=com.comphenix.protocol.scheduler.DefaultTask@226e0f0b
tickCounter=20
configExpectedMod=1
updater=
redirectHandler=com.comphenix.protocol.ProtocolLib$2@64e7cb06
scheduler=com.comphenix.protocol.scheduler.DefaultScheduler@53460efc
commandProtocol=com.comphenix.protocol.CommandProtocol@68520e18
commandPacket=com.comphenix.protocol.CommandPacket@3a96424e
commandFilter=com.comphenix.protocol.CommandFilter@60f311e1
packetLogging=com.comphenix.protocol.PacketLogging@3a1c2ed
skipDisable=false
isEnabled=true
loader=org.bukkit.plugin.java.JavaPluginLoader@7b7b2e4f
server=CraftServer{serverName=CraftBukkit,serverVersion=3871-Bukkit-3f9263b,minecraftVersion=1.20.1}
file=plugins/ProtocolLib (1).jar
description=org.bukkit.plugin.PluginDescriptionFile@73f7875c
dataFolder=plugins/ProtocolLib
classLoader=org.bukkit.plugin.java.PluginClassLoader@12267ddc
naggable=true
newConfig=YamlConfiguration[path='', root='YamlConfiguration']
configFile=plugins/ProtocolLib/config.yml
logger=org.bukkit.plugin.PluginLogger@6c8e1f3
]
Version:
ProtocolLib v5.1.0
Java Version:
17.0.8
Server:
3871-Bukkit-3f9263b (MC: 1.20.1)

[19:19:48] [Server thread/INFO]: Error Cannot perform automatic updates. (java.lang.NullPointerException: Cannot invoke "com.comphenix.protocol.updater.Updater.isChecking()" because "this.updater" is null) occurred in ProtocolLib v5.1.0.
[19:19:48] [Server thread/ERROR]: [ProtocolLib] INTERNAL ERROR: Cannot perform automatic updates.
If this problem hasn't already been reported, please open a ticket
at https://github.com/dmulloy2/ProtocolLib/issues with the following data:
Stack Trace:
java.lang.NullPointerException: Cannot invoke "com.comphenix.protocol.updater.Updater.isChecking()" because "this.updater" is null
at com.comphenix.protocol.ProtocolLib.checkUpdates(ProtocolLib.java:540)
at com.comphenix.protocol.ProtocolLib.lambda$createPacketTask$0(ProtocolLib.java:511)
at org.bukkit.craftbukkit.v1_20_R1.scheduler.CraftTask.run(CraftTask.java:77)
at org.bukkit.craftbukkit.v1_20_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:414)
at net.minecraft.server.MinecraftServer.b(MinecraftServer.java:1208)
at net.minecraft.server.dedicated.DedicatedServer.b(DedicatedServer.java:374)
at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:1155)
at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:980)

ProtocolLib 5.1.0 does not support Minecraft 1.20.1. Please use the latest release of ProtocolLib: https://github.com/dmulloy2/ProtocolLib/releases/download/5.1.0/ProtocolLib.jar.