Can't union ANYTHING in my game

Anything I try to union in my game disappears and I don’t know how to fix it. Even the absolute most basic stuff I can’t attatch to squares via unioning without them turning invisible and getting an error that says something like mesh manager: http request failed After some googling I see some other get this problem but I don’t know how to fix it! It’s so infuriating I can’t use any unions whatsoever!

If anyone know how to fix this I would be eternally grateful.


Use blender for creating complex shapes, and don’t use unions for simple operations like joining two cubes together.

Unions as of now are pretty unreliable.


Try disabling CSGV2 in Studio’s physics settings.

I’ve never used blender and I’m not trying to make anything complex.

These are literally the only 2 things I’m trying to union the square was just me seeing if it would work:

They union just fine, but then when I try to save the game they disappear or if I ununion them they disappear.

Did not work thanks for the suggestion.

Hi, this is my first post on the dev forum but anyways, here we go!
I have this multiple times happen to me, usually the unions are corrupt.
When this happens to me,
I start doing a series of troubleshooting mesures:

  • Open the place locally
  • Close all windows of studio and reopen the place in question
  • Check internet connection
  • Restart computer
  • And finally as my last resort, I just close down studio, wait for a couple hours or one to two days and reopen the place and it usually fixes.
    And if all of this dosen’t help, we’ll I just have to restart the union.
    However, if this behaviour is happening on all unions that you do, there is a problem there.
    I recommend to reinstall Studio, check your internet connection and preferably build locally.
    I hope this helps!

It does happen with EVERY union I try to make. I reinstalled studio like you suggested and it seemed to help a bit but it really just gave me a different problem. The target I made just turns orange throughout basically defeating the purpose of making it a union.

There is a setting for a union, in properties that you can uncheck to have the original colors of the union, instead of being the unified color from the Color selector.
It’s the « Use Part Color » setting and it should be unchecked to see the original colors of the union.


This is not a bug. You can only union bricks.

What do you mean bricks? As in non circles and cylinders? I’ve had no trouble in the past unioning those, and also I can’t union ANYTHING like my title says including bricks. Also I CAN union the things above it’s just buggy and they disappear.

If you are trying to union meshes, it wont work
@DMCPEPlays probably means BaseParts which are bricks, cylinders, spheres and trusses etc, but not meshes (including if there is a mesh in the brick)

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Yeah there’s definitely no meshes in those parts

You should be able to union Cylinders, Blocks, Balls and Wedges from the default ROBLOX part selection. Could you send a photo of the whole studio screen, including the explorer, properties window, of what you are trying to union, and the result of the union?

It’s a pretty common thing called corrupted unions, it’s been here for a while now. So, I’d recommend you to use meshes instead of unions to prevent them from disappearing. I hope roblox staff member’s fixes it soon.
Thank you, I hope this helps.

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My guess is that the alignment of your parts are causing this issue. You should ensure parts do not have tiny offsets from each other (e.g. 0.01 studs apart). You want the parts aligned as close together as they possibly can be. Another thing you can try is duplicating/copying the union before it has caused an issue.

Can you save a sample union to rbxm and rbxmx files before restarting and after restarting studio and upload them? This could be related to corrupted union data, and if so, I should be able to take a look at its contents. Occasionally unions can completely clear their data for no apparent reason, however, sometimes the data exists and is actually recoverable in rare cases.

Unions store two sections of data: Child Data and Model Data. Child data stores the “separated” union, and when this is cleared, it causes the union to break. It sounds like this is your issue since you can’t separate them. This data can be cleared due to invalid instances being unioned somehow or another, or simply corruption (weirdly unions automatically delete invalid contents rather than producing an error, and manually adding random non-part instances with an external tool will cause this for example). Their model data, obviously, stores information about the union’s appearance. If this data gets messed up the union will appear invalid, or not appear at all, however ususally it will error or just not appear.

Fun fact: You can extract scripts, including their sources from unions due to them essentially embedding a mini rbxm file within themselves, and you can even do so from a live game without exploits due to how Roblox caches these files.

Lastly, you should most likely not disable CSGV2. CSGV2 actually improves upon this issue and tends to be more reliable.


MeshParts are also BaseParts :wink:

In my experience, it’s impossible.

You just can’t stick two bricks together in a union, and you can’t stick two unions together in a model. Those are just the rules of the land, for some reason.

But you can use negative parts once in a blue moon, so at least we have that.

Maybe rejoin your place. I used to have this glitch, mainly when I was in team create. If that doesn’t help, obviously, contact a hr

How can one extract scripts? Is there a way to edit the script within that union so I could somehow internally fix a corrupted or broken union?

I think you misunderstood my reply, that isn’t related to corrupted unions. You can union parts with scripts in them and recover the source from those scripts by separating the unions. This also includes server scripts, you can insert a server script, and, when Roblox goes to download the union, you can take the cached union data from the Roblox cache folder and extract that script’s source, which works in published games. This is just a side effect of how unions work, their Child Data is in exact same format as an rbxm file, and this is how Roblox handles the Separate action on Unions.

As for corrupted unions, if you duplicate your union (ctrl+d) and attempt to separate it, but nothing comes up, the data is unfortunately lost. If the union does properly separate, you can just hit the Union button to reunion them. Otherwise, you should try one of the resources like this one: How to recover invisible / corrupt unions