'/data remove' can't remove the NBT "CustomName"

Does reloading the world (leave and enter) fix it?

No, its nbt still has CustomName value
It still exist in 18w15a

Comfirmed in 18w16a

You can update the affected versions yourself, no need to comment.

Confirmed for Minecraft 1.13-pre7

Affects 18w31a.

Affects 1.13.1-pre2.

Confirmed for 18w43c

Confirmed for 1.14.1

Confirmed in 1.16 Pre-release 2.

Just to make it clear – this seems to be general. I can't remove saddles from horses, items from frames, ...

Can confirm in 21w05b.

Can confirm in 21w06a.

As a workaround you can just use data modify to set it to any non-JSON string, it will throw and end up clearing the existing name

Can confirm in 1.17.1. Video attached.

@tryashtar can you give an example? I find that the the non-JSON string is simply rejected by the command parser and so never executed. And, say, to remove horse armor I've tried things like setting the specific armor slot to "air" or to Count:0, which don't work.

/summon pig ~ ~ ~ {CustomName:'"test"'}
/execute as @e[type=pig,name=test] run data modify entity @s CustomName set value ""

Ah, yes, thanks, good to have this in the text!

I agree that this works for CustomName, and I'd guess for other string properties.

However, my bug was marked a dup of this one, and I was looking at non-string properties, such as SaddleItem. And it does not work (afaict) for a horse's SaddleItem. I tried

/data modify entity f4d501d5-adc6-4bff-8d79-07924348f0a5 SaddleItem set value ""
/data modify entity f4d501d5-adc6-4bff-8d79-07924348f0a5 SaddleItem set value {id:""}
/data modify entity f4d501d5-adc6-4bff-8d79-07924348f0a5 SaddleItem set value {id:"",Count:0b}
/data modify entity f4d501d5-adc6-4bff-8d79-07924348f0a5 SaddleItem set value {id:"",Count:0}

Other things that don't work: {} {id:"\"\""}

So it's a workaround for some cases, but not all I'm afraid.

Following up, I have found that my specific problem about saddles can be solved using the /item command, as in:

/item replace entity @e[tag=armor_horse] horse.saddle with air

For some reason, there is no "remove" subcommand of item

This is not a general answer, it only works for attributes that are supported in the item command, but it's a workaround for some cases.

Requesting ownership of this ticket since the current reporter has been inactive since May of 2019. I'm willing to keep this report updated and will continue to provide all of the necessary information. 🙂

Can confirm in 1.18.1.

Can confirm in 1.18.2 and 22w13a.

Can confirm in 1.19.

Just stumbled upon this bug myself. Made me very confused as to why my functions weren't working properly for a couple days before I realized this command simply just wasn't working. But I've found for the time being, an easy fix is instead of running /data remove entity @s CustomName, use /data modify entity @s CustomName set value ''

Can confirm in 1.19.1 Pre-release 4.

Can confirm in 1.19.1 Release Candidate 2

Can confirm in 1.19.1

Can confirm in 1.19.2 Release Candidate 1

Relates to MC-179815, MC-153392, MC-122008, MC-207605, MC-135044, MC-248264.

Can confirm in 23w43a / 1.20.2: requesting ownership to make it easier to update (the OP has been inactive since 05/2019).

This is now a crucial problem I think.
Removing CustomName is now outright impossible to do due to MC-267259

@unknown: Stop reposting information that adds nothing new to the report. Everything you have to say has already been said (MC-267259 included), and every comment sends unnecessary email notifications to watchers.
Yes, MC-267259 is a thing, and is working as intended, and yes, this issue (MC-128225) is a more important problem now, as already stated by @unknown in this comment. That's why the Mojang Priority for this ticket has been bumped from "Low" to "Important".

[Mod] Turbo I get It. I was just trying to get a reason why my messages were removed. Thank you for explaining

Can confirm in 24w06a

Just did a quick code analysis and it seems like this bug could be solved like this:

net.minecraft.world.entity.Entity

public void load(CompoundTag tag) {
    // ...
    if (tag.contains("CustomName", Tag.TAG_STRING)) { // Existing code, line 1933
        String text = tag.getString("CustomName");
        try {
            setCustomName(Component.Serializer.fromJson(text));
        } catch (Exception ex) {
            LOGGER.warn("Failed to parse entity custom name {}", text, ex);
        }
    } else { // Fix
        setCustomName(null);
    }
    // ...
}

A similar fix can also be applied to other places, specifically command blocks, containers, beacons, banners and enchanting tables.

An alternative way would be to make a method dedicated to retrieving a custom name, with the same code as above, that returns the custom name.

The fix comes from removing the custom name if the tag is not present. Through testing, this seems to work as expected, /data remove does remove the custom name, other types of changes also don't cause any issues.

Can confirm in 24w07a and 24w09a

Can confirm in 24w10a, 24w11a, 24w12a and 24w13a

This still exists all the way up to 1.20.5 Prerelease 3.

Still exist in 1.20.5-rc1.
It seems like we won't be able to remove custom names for 2 versions in a row after having been able to in another way since 1.13. Ouch.

Still exists in 1.20.5-rc2.

Sadly, this is still the case in Release 1.20.5.

Still exists in 1.20.6-rc1. Is this even a critical bug?

Confirmed in 1.21.2

Confirmed in 1.21.3