[MC-131562] Pressing the "Done" button in empty command block minecarts prints the message "Command set:" in chat

The Bug:

Pressing the "Done" button in empty command block minecarts prints the message "Command set:" in chat.

Steps to Reproduce:

Summon a command block minecart by using the command provided below.
```
/summon minecraft:command_block_minecart ~ ~ ~
```
Open it up and press the "Done" button.
Take note as to whether or not pressing the "Done" button in empty command block minecarts prints the message "Command set:" in chat.

Observed Behavior:

Pressing the "Done" button in empty command block minecarts prints the message "Command set:" in chat.

Expected Behavior:

Pressing the "Done" button in empty command block minecarts would not print the message "Command set:" in chat. Instead, no message should be printed at all, as no command has been inserted into the command block minecart.

Attachments

MC-131562.mp4

Comments 25

tryashtar 2018-06-17T18:18:01Z

Cannot reproduce, both make messages for me

tryashtar 2018-06-17T18:25:46Z

Oops, my mistake, I can reproduce now. Haha, sorry about that

Kraif 2018-07-13T12:19:44Z

Confirmed for 1.13-pre8.

Kraif 2018-07-17T10:08:27Z

Confirmed for 1.13-pre9.

Kraif 2018-07-18T10:54:37Z

Confirmed for 1.13-pre10.

15 more comments

Conem 2020-06-07T19:12:46Z

Confirmed in 1.16 Pre-release 2.

Conem 2020-06-10T18:34:38Z

Confirmed in 1.16-pre3.

Conem 2020-06-11T18:49:47Z

Confirmed in 1.16-pre4.

Conem 2020-06-12T15:29:30Z

Confirmed in 1.16-pre5.

Conem 2020-06-15T20:54:44Z

Confirmed in 1.16-pre6.

Conem 2020-06-17T09:07:50Z

Confirmed in 1.16-pre7.

Conem 2020-06-18T11:55:01Z

Confirmed in 1.16-pre8.

Conem 2020-06-19T14:12:42Z

Confirmed in 1.16-rc1.

Avoma 2020-12-27T13:51:04Z

Can confirm in 20w51a.

Avoma 2021-02-16T17:13:49Z

Can confirm in 21w06a.

Avoma 2021-02-27T13:42:34Z

Can confirm in 21w08b. Video attached.

Justin Zheng 2021-02-27T15:24:41Z

Same with command blocks

Avoma 2021-03-01T17:15:19Z

Can confirm in 1.16.5. @unknown, are you sure? I'm almost certain that this can only be reproduced with command block minecarts.

Conor Byrne 2021-03-03T16:21:12Z

I've taken a look at the code, and the fix seems to be quite simple.

In a normal command block, a check is done to see if the string is empty beforehand (yarn mappings):

ServerPlayNetworkHandler#onUpdateCommandBlock

commandBlockExecutor.markDirty();
if (!ChatUtil.isEmpty(string)) {
   this.player.sendSystemMessage(new TranslatableText("advMode.setCommand.success", new Object[]{string}), Util.NIL_UUID);
}

But, in a minecart command block, the implementation is different (yarn mappings):

ServerPlayNetworkHandler#onUpdateCommandBlockMinecart

commandBlockExecutor.markDirty();
this.player.sendSystemMessage(new TranslatableText("advMode.setCommand.success", new Object[]{packet.getCommand()}), Util.NIL_UUID);

This issue can easily be solved by only calling sendSystemMessage if ChatUtil#isEmpty returns false like a normal command block

Marty McFly 2021-06-09T13:19:16Z

Affects 1.17

Avoma 2021-08-31T12:11:30Z

Can confirm in 1.17.1.

Marty McFly 2021-10-12T15:48:14Z

Affects 21w40a

Avoma 2021-10-19T10:31:48Z

Can confirm in 21w41a. The expected behavior would be that upon pressing the "Done" button in a command block minecart without a command in it, no message would be printed into the chat.

NULLYUKI 2023-12-04T22:14:01Z

Can confirm in 1.20.3 Release Candidate 1

Bolshi 2025-07-26T09:42:13Z

Still in 1.21.8