Stopping a Play Solo session while one of a WeldConstraint's parts are parented to nil will crash studio

[XAXA]

• Describe the bug. Describe what is happening when the bug occurs. Describe what you would normally expect to occur.

Stopping a Play Solo session while one of a WeldConstraint’s parts are parented to nil will crash studio.

( EDIT: This will also crash a server instance when it’s closed in studio. )

• How often does the bug happen (Everytime/sometimes/rarely)? What are the steps that reproduce the bug? Please list them in very high detail. Provide simple example places that exhibit the bug and provide description of what you believe should be the behavior.

This crash can be reproduced reliably. Start a new project and create a script in workspace with the following source:

local p = Instance.new("Part", workspace)
local d = Instance.new("Part")
local w = Instance.new("WeldConstraint", p)
w.Part0 = p
w.Part1 = d

Hit Play Solo on studio and then stop the session. This should cause a crash.

• Where does the bug happen (www, gametest, etc) Is it level-specific? Is it game specific? Please post a link to the place that exhibits the issue.

This happens on the latest version of studio as of posting this.

• When did the bug start happening? If we can tie it to a specific release that helps us figure out what we broke.

I don’t know. I experienced this on the latest version of studio.

• Anything else that you would want to know about the bug if it were your job to find and fix it.

Running on Windows 10.

[XAXA]

It is a crash in studio.

@CodeWriter

Critical bugs

If you have a critical bug that urgently needs to be investigated, start your post with the phrase “ROBLOXCRITICAL”. This is used to alert admins right away to the issue. A critical bug must satisfy at least one of the following criteria:

• A reproducible crash (Studio, game or website shutting down or returning a fatal error 100% of the time when a set of steps are followed)
• Loss of data (either through Data Stores or Data Persistance)
• Exploits
• Preventing all players from connecting to a game and affecting multiple Roblox games.

[Coasterteam]

Can confirm. This happens to me as well.

[AbstractAlex]

@XAXA

It is a crash in studio.

The robloxcritical guidelines are intentionally vague so that you can use discretion. There was an incident in the past where users weren’t sure if a bug should have been marked critical (it was) because the critical guidelines were too specific.

Personally, I see “ROBLOXCRITICAL” as “this needs immediate, emergency attention for the sake of the platform”
Such as major crash rates, textures not loading on meshparts, purchases failing, datastores down, etc.

[nsgriff (griffted)]

I will submit this as a bug, but please remove the ROBLOXCRITICAL tag from this post. This does not need to be urgently investigated and is not critical enough to call in engineers on a weekend to fix. Thanks.