New unions disappear with Mesh Manager HTTP 404 error after publishing

After publishing, unions created in that session of Studio before the last time you published will disappear and a 404 error will be printed in the Output widget. Studio must be restarted to make this union reappear (but otherwise the union appears to be fine ingame).

I started noticing this on April 18, 2020.
My video and log file were produced around now: April 20, 2020, 22:00 (GMT-5)

This consistently happens to me every time I open Studio and work on my project, and happens to me in a default baseplate. To reproduce, I just have to make a union and publish the game.

21:57:07.668 - Mesh Manager: http request failed, contentid: ‘’, exception: HTTP 404 (Not Found)

Private log file:


Can you see if opening this place, the Unions work again? I encountered something similar and after 20 minutes it fixed itself. This would not be a solution, but would help me gather info about the problem.


Reopening the place without restarting Studio does not make the unions reappear (even after waiting ~20 minutes). Only restarting Studio makes them reappear.


Thank you, this is useful. I’m going to reach out to people who work on the asset-fetching on the engine to see if they know what is going on.


To add onto this issue, there is certainly something wrong with Studio handling undo in this case. When undoing after the union turns invisible from the above issue, internally the solidmodel assetID is wiped. If you publish again afterwards, this union is permanently invisible.

I made a model yesterday (16:41, GMT-5) in this game (two unioned hollow cylinders) and this temporary disappearing issue occurred. After publishing and seeing the unions go invisible, I just pressed undo to make them visible again (which works for some reason) and repeated my last action and saved and published the game again. In a real server joined via the website shortly afterwards, the unions were invisible but still physically there, and are still like this the next day. This sounds a lot like this issue, but this particular version of it seems related to this issue given how it reproduces closely alongside, and reproduces reliably.

If I export this asset after publishing and seeing it turn invisible, the solidmodel assetID for the Union is this:
<Content name="AssetId"><url></url></Content>

If I export this asset after undoing and re-publishing, the solidmodel assetID for the Union is this:
<Content name="AssetId"><null></null></Content>

I’ve added a log file to the DM for this scenario.

Repro for this:

Just now, 14:40 (GMT-5), I create a union, rename it, publish, undo because it turned invisible, re-rename it, publish again.

I go to this same place ingame off the website and it is immediately completely invisible.

If I close and reopen the game in Studio without restarting Studio, the union is still visible.
If I close Studio entirely and reopen it, the union is now invisible.

This is strange because the issue above did not happen to me initially when I reported the issue in this thread, and I’m pretty sure I was using the same publish > undo > repeat action > publish again workaround.

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It happens to me too. I usually restart my pc when I got this error. Thats gets fixed.

I’d restart your pc, this happened to me one time and it was so annoying but when I restarted my pc, it all just went away.

I have the same issue except the meshes and images I import don’t load in until I restart Studio.

I’ve seen this sort of problem as well.

When someone in team create decides to union something, it disappears from my screen and sometimes for others.

The only fix we found was to rejoin studio.

Edit: The reason for error is because Studio attempts to fetch the mesh ID before it’s finished uploading in private places. Why it does this is unknown.

This has previously been presented three years ago, but there’s still no fix. I also have more information to add. Here’s the original post.

In Studio, if you try to upload a union to Roblox in a private game, it turns invisible in the game. You cannot place the union again in the place, as it immediately turns invisible. I found that if you upload the union in the private place and you try to implement the union in a different public game, it is fine. The topic I linked has an error uploading with offline use of Studio, which I haven’t tested yet, but it failed to find the error in a private place. I have linked an unlisted YouTube video showing how to recreate the error:

As shown in the video, the union was created in a private place. After publishing it to Roblox, it turns invisible in-game. I then showed me putting it back in the game, which keeps it invisible. Then, I exit out and implement it in a public game. It is then fine in the other game.

Hopefully this (at least) three year old bug can get fixed! It’s easy to avoid, but really confusing if you stumble upon it by accident.

If you have any questions, reply and I can try to further explain it. Let me know if any of you have recreated the bug. Thanks!


Did you union it too much? That might be the case. Unions can’t render when it’s been union and negate too much.

You have your output closed. By chance, does the output display an HTTP error after publishing?

I’ve noted odd behavior where it attempts to acquire its asset ID before the actual web-end data is ready after publishing, resulting in an error where it can’t acquire the mesh due to the ID not existing quite yet. I wonder if you are having the same problem.

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No, I thought that was originally the case but when I recreated it I unionized it one time, then published it. The video shows that.

I’ll go ahead and try to see if there’s an error there. I’ll make another post when I get the results.

Alright so I went back into studio and you’re right. Studio displays the error log that SolidModelContentProvider could not fetch the asset ID, though it wasn’t created yet. Here’s a video including the output. Notice how at 2 seconds in, the error message pops up, but the union is clearly not finished creating yet. Not sure why this only happens in private places, but it looks like Studio needs to wait until the asset is finished uploading before trying to fetch the mesh ID. Thanks for pointing me in the right direction!

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I encountered this too i saved my game and the unions went invisible so i pressed undo and i saved it again but when i restarted studio the unions were all invisible and im not sure how I can get them back.
I get this when i insert it into another studio image
And this too image

Did you upload the union itself to Roblox or just the place? Also, was the place set to private?

It was a published place which after i published the unions went so i pressed undo and then published again. after i re opened studio the unions were gone.