• This issue is not solved in a development build

Describe the bug

[21:54:01 ERROR]: Couldn't register custom payload
java.lang.IllegalArgumentException: Channel must contain : separator (attempted to use )
at org.bukkit.plugin.messaging.StandardMessenger.validateAndCorrectChannel(StandardMessenger.java:503) ~[paper-api-1.20.4-R0.1-SNAPSHOT.jar:?]
at org.bukkit.craftbukkit.v1_20_R3.entity.CraftPlayer.addChannel(CraftPlayer.java:2504) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.server.network.ServerCommonPacketListenerImpl.handleCustomPayload(ServerCommonPacketListenerImpl.java:135) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.network.protocol.common.ServerboundCustomPayloadPacket.handle(ServerboundCustomPayloadPacket.java:46) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.network.protocol.common.ServerboundCustomPayloadPacket.a(ServerboundCustomPayloadPacket.java:12) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.network.protocol.PacketUtils.lambda$ensureRunningOnSameThread$0(PacketUtils.java:54) ~[?:?]
at net.minecraft.server.TickTask.run(TickTask.java:18) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.util.thread.BlockableEventLoop.doRunTask(BlockableEventLoop.java:153) ~[?:?]
at net.minecraft.util.thread.ReentrantBlockableEventLoop.doRunTask(ReentrantBlockableEventLoop.java:24) ~[?:?]
at net.minecraft.server.MinecraftServer.doRunTask(MinecraftServer.java:1465) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.server.MinecraftServer.d(MinecraftServer.java:194) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.util.thread.BlockableEventLoop.pollTask(BlockableEventLoop.java:126) ~[?:?]
at net.minecraft.server.MinecraftServer.pollTaskInternal(MinecraftServer.java:1442) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.server.MinecraftServer.pollTask(MinecraftServer.java:1365) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.util.thread.BlockableEventLoop.managedBlock(BlockableEventLoop.java:136) ~[?:?]
at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1516) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1226) ~[paper-1.20.4.jar:git-Paper-458]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:319) ~[paper-1.20.4.jar:git-Paper-458]
at java.lang.Thread.run(Thread.java:1589) ~[?:?]
[21:54:01 INFO]: Test lost connection: Invalid payload REGISTER!

Version Info
https://pastebin.com/FCFLzy0B