not work on 1.16.5

[FierceManul]

After command input, no pop-up window.

[DoomSquirter]

same here. relevant log snippet:
[07May2021 07:04:30.748] [Render thread/FATAL] [net.minecraft.util.concurrent.ThreadTaskExecutor/]: Error executing task on Client java.awt.HeadlessException: null at java.awt.GraphicsEnvironment.checkHeadless(Unknown Source) ~[?:1.8.0_261] at java.awt.Window.<init>(Unknown Source) ~[?:1.8.0_261] at java.awt.Frame.<init>(Unknown Source) ~[?:1.8.0_261] at javax.swing.JFrame.<init>(Unknown Source) ~[?:1.8.0_261] at malte0811.nbtedit.gui.NBTFrame.<init>(NBTFrame.java:51) ~[nbtedit:?] at malte0811.nbtedit.network.MessageOpenWindow.onMessage(MessageOpenWindow.java:30) ~[nbtedit:?] at net.minecraftforge.fml.network.simple.IndexedMessageCodec.lambda$tryDecode$3(IndexedMessageCodec.java:128) ~[forge:?] at java.util.Optional.ifPresent(Unknown Source) ~[?:1.8.0_261] at net.minecraftforge.fml.network.simple.IndexedMessageCodec.tryDecode(IndexedMessageCodec.java:128) ~[forge:?] at net.minecraftforge.fml.network.simple.IndexedMessageCodec.consume(IndexedMessageCodec.java:162) ~[forge:?] at net.minecraftforge.fml.network.simple.SimpleChannel.networkEventListener(SimpleChannel.java:80) ~[forge:?] at net.minecraftforge.eventbus.EventBus.doCastFilter(EventBus.java:247) ~[eventbus-4.0.0.jar:?] at net.minecraftforge.eventbus.EventBus.lambda$addListener$11(EventBus.java:239) ~[eventbus-4.0.0.jar:?] at net.minecraftforge.eventbus.EventBus.post(EventBus.java:302) ~[eventbus-4.0.0.jar:?] at net.minecraftforge.eventbus.EventBus.post(EventBus.java:283) ~[eventbus-4.0.0.jar:?] at net.minecraftforge.fml.network.NetworkInstance.dispatch(NetworkInstance.java:86) ~[forge:?] at net.minecraftforge.fml.network.NetworkHooks.lambda$onCustomPayload$1(NetworkHooks.java:90) ~[forge:?] at java.util.Optional.map(Unknown Source) ~[?:1.8.0_261] at net.minecraftforge.fml.network.NetworkHooks.onCustomPayload(NetworkHooks.java:90) ~[forge:?] at net.minecraft.client.network.play.ClientPlayNetHandler.func_147240_a(ClientPlayNetHandler.java:1904) ~[?:?] at net.minecraft.network.play.server.SCustomPayloadPlayPacket.func_148833_a(SCustomPayloadPlayPacket.java:59) ~[?:?] at net.minecraft.network.play.server.SCustomPayloadPlayPacket.func_148833_a(SCustomPayloadPlayPacket.java:11) ~[?:?] at net.minecraft.network.PacketThreadUtil.func_225383_a(SourceFile:21) ~[?:?] at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213166_h(SourceFile:144) ~[?:?] at net.minecraft.util.concurrent.RecursiveEventLoop.func_213166_h(SourceFile:23) ~[?:?] at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213168_p(SourceFile:118) ~[?:?] at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213160_bf(SourceFile:103) ~[?:?] at net.minecraft.client.Minecraft.func_195542_b(Minecraft.java:947) ~[?:?] at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:607) ~[?:?] at net.minecraft.client.main.Main.main(Main.java:184) ~[minecraft-1.16.5-client.jar:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_261] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_261] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_261] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_261] at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) ~[forge-1.16.5-36.1.13-launcher.jar:36.1] at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-8.0.9.jar:?] at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-8.0.9.jar:?] at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-8.0.9.jar:?] at cpw.mods.modlauncher.Launcher.run(Launcher.java:82) [modlauncher-8.0.9.jar:?] at cpw.mods.modlauncher.Launcher.main(Launcher.java:66) [modlauncher-8.0.9.jar:?] at io.github.zekerzhayard.forgewrapper.installer.Main.main(Main.java:50) [ForgeWrapper-1.4.2.jar:?] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_261] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_261] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_261] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_261] at org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:196) [NewLaunch.jar:?] at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:231) [NewLaunch.jar:?] at org.multimc.EntryPoint.listen(EntryPoint.java:143) [NewLaunch.jar:?] at org.multimc.EntryPoint.main(EntryPoint.java:34) [NewLaunch.jar:?]