Bug in 31.0.2 when using multiple instance

[Sigma3Wolf]

Hi, I'm currently using 30.2.3 because all newer version got a bug when using multiple instance.

abstract:
I'm using 1 obs instance for virtual camera, while the second instance record my screen.
This is usefull for using virtual camera in Zoom or Team, while recording the said team.

Since obs 31.0, this is no longuer possible.
if you launch 2 instance in 31.0.2, 2 bugs occurs.
1. first bug: The html Dock for Lowerthirds doesn't load on second instance
2. when you try to CLOSE the second instance, it doesn't do anything. You need to reboot the computer.

I have tried all release after 30.2.3, none work.
If I could avoid using a second instance I wouldn't mind, but it's not possible since I'm not recording the virtual camera, I'm only recording my screen.
any reason why this occur in the latest 31.xx version ?

 

[prgmitchell]

Hi, I'm currently using 30.2.3 because all newer version got a bug when using multiple instance.

abstract:
I'm using 1 obs instance for virtual camera, while the second instance record my screen.
This is usefull for using virtual camera in Zoom or Team, while recording the said team.

Since obs 31.0, this is no longuer possible.
if you launch 2 instance in 31.0.2, 2 bugs occurs.
1. first bug: The html Dock for Lowerthirds doesn't load on second instance
2. when you try to CLOSE the second instance, it doesn't do anything. You need to reboot the computer.

I have tried all release after 30.2.3, none work.
If I could avoid using a second instance I wouldn't mind, but it's not possible since I'm not recording the virtual camera, I'm only recording my screen.
any reason why this occur in the latest 31.xx version ?

This isn't considered a bug, if you are running multiple instances of OBS you should be running each additional instance in portable mode to avoid issues like this.

Running in Portable Mode | OBS

OBS (Open Broadcaster Software) is free and open source software for video recording and live streaming. Stream to Twitch, YouTube and many other providers or record your own videos with high quality H264 / AAC encoding.

obsproject.com

 

[AaronD]

I use multiple simultaneous instances natively, not portable. Each one has command-line options to use different profiles and scene collections.

Have a shortcut for each, and modify them to tack this on the end of the command:
--multi --profile "Name" --collection "Name"
Different Name for each, of course, that corresponds to what you call them in OBS.

Run the same command in the Command Prompt, with --help on the end instead, to see all that you can do there. :-)

 

[Zippo2025]

Hi, I'm currently using 30.2.3 because all newer version got a bug when using multiple instance.

abstract:
I'm using 1 obs instance for virtual camera, while the second instance record my screen.
This is usefull for using virtual camera in Zoom or Team, while recording the said team.

Since obs 31.0, this is no longuer possible.
if you launch 2 instance in 31.0.2, 2 bugs occurs.
1. first bug: The html Dock for Lowerthirds doesn't load on second instance
2. when you try to CLOSE the second instance, it doesn't do anything. You need to reboot the computer.

I have tried all release after 30.2.3, none work.
If I could avoid using a second instance I wouldn't mind, but it's not possible since I'm not recording the virtual camera, I'm only recording my screen.
any reason why this occur in the latest 31.xx version ?

Hi Sigma3Wolf ! Another kind user pointed me to your post made yesterday ( March 11, 2025 ) I opened OBS this morning and the exact same thing happened to me when I upgraded to the newest version ( version 31.0.2 ) What you describe is my experience exactly. That lower 1/3 of the screen has disappeared, only way to bring it back was to go up to the top menu and choose reset UI. However nothing else worked, I couldn't even exit out of that instant. I have been running 8 LIVE streams on YouTube for just over a year, every single day and have never encountered that problem... until now with this new version. I reverted to the previous version and bingo, everything is working fine again. I have no idea where to post this to the people who make the problem. This of course *is indeed a bug * ... if multiple instances worked fine the way I've been doing it for a year and now it doesn't work, for me, that's a bug, or error in the program. Programmers have broken something there. Anyway for now I'm running the version just prior to this one and all is well again. I have 8 streams running on my PC without a problem. So glad that it wasn't just me experiencing this. I am surprised that with not many have been posting about this problem with I'm sure thousands streaming multiple streams as I do.

 

[Sigma3Wolf]

Hi Sigma3Wolf ! Another kind user pointed me to your post made yesterday ( March 11, 2025 ) I opened OBS this morning and the exact same thing happened to me when I upgraded to the newest version ( version 31.0.2 ) What you describe is my experience exactly. That lower 1/3 of the screen has disappeared, only way to bring it back was to go up to the top menu and choose reset UI. However nothing else worked, I couldn't even exit out of that instant. I have been running 8 LIVE streams on YouTube for just over a year, every single day and have never encountered that problem... until now with this new version. I reverted to the previous version and bingo, everything is working fine again. I have no idea where to post this to the people who make the problem. This of course *is indeed a bug * ... if multiple instances worked fine the way I've been doing it for a year and now it doesn't work, for me, that's a bug, or error in the program. Programmers have broken something there. Anyway for now I'm running the version just prior to this one and all is well again. I have 8 streams running on my PC without a problem. So glad that it wasn't just me experiencing this. I am surprised that with not many have been posting about this problem with I'm sure thousands streaming multiple streams as I do.

Hi Zippo2025,
thanks for your post.

Yes, I also disagree with prgmitchell, who claim it's not a bug.
it has worked since "forever", I have been using OBS for more then 10 years. not an issue prior to last version.
Furthermore, the "html" dock file is "sharable", not locked, should work and the fact that OBS "refuse to stop", "leak in memory" and make "Windows Unresponsive" shouldn't happen EVEN if a feature is not supported.

I'm a programmer myself, if I want to prevent a user from staring multiple instance of my program, I can do it, if I allow it it's because it's safe to do so. I don't think prgmitchell really understood the issue at end here.

using OBS to do 2 completely different task, doesn't interfer with one another and shouldn't cause that kind of issue.
I believe the code was messed up by the update.

I must also point out... I'm not using the html dock in the second instance, so I removed it to check it out and OBS still crash on exit when running the second instance. The issue is NOT the plugin, it's with OBS itself.

and I don't know what to think when someone claiming a memory leak "is not a bug"

 

[Fenrir]

To clarify, what was previously happening was extremely unsafe, and not ever supported.

We, effectively, fixed a bug that allowed it to even occur in the first place. We understand that a very small number of users have come to rely on the old bug for their workflows, but we will not be reintroducing this behavior. If multiple instances of OBS are required to be run at the same time, then portable mode should be used to avoid data loss and corruption of settings.

 

[AaronD]

To clarify, what was previously happening was extremely unsafe, and not ever supported.

We, effectively, fixed a bug that allowed it to even occur in the first place. We understand that a very small number of users have come to rely on the old bug for their workflows, but we will not be reintroducing this behavior. If multiple instances of OBS are required to be run at the same time, then portable mode should be used to avoid data loss and corruption of settings.

What about the --multi flag on the command line? Isn't this what it's for? Along with different --profile and --collection names?

 

[Fenrir]

--multi is, Frankly? A mistake, that we've considered removing. It was added because a single person during a beta test period complained about the new warning dialog. All the option does is suppress the dialog, but I agree it shouldn't be there, and likely never should have been merged.

Launching OBS with a specific scene collection or profile has plenty of uses with a single instance.

 

[AaronD]

--multi is, Frankly? A mistake, that we've considered removing. It was added because a single person during a beta test period complained about the new warning dialog. All the option does is suppress the dialog, but I agree it shouldn't be there, and likely never should have been merged.

Launching OBS with a specific scene collection or profile has plenty of uses with a single instance.

Hmm... I rely on that pretty heavily for some of my rigs. Those three flags with a bunch of others too, starting multiple simultaneous instances of OBS from a script. And a DAW, and some other things too. Each instance has a different job, with different profiles and collections, and there's enough going on that I really can't combine them into a single instance very well, nor is there space to add a second machine. The single machine keeps up just fine with all that.

I can see the question coming of, "How do you control all that? What's the point if you can't control it?" The answer is automation, with the Advanced Scene Switcher plugin. The Master instance of OBS produces a polished stream like usual, operated manually. The Slave instance of OBS and the DAW both receive messages from Adv. SS, which keys off of a naming convention for the Master's scenes. So the operator only has to be concerned with the Master, and everything else just follows along.

If I could have two independent sets of scene switching, with the virtual camera, projector, and encoder all fed from either one as independent selections, then I might be able to combine them. The Downstream Keyer plugin doesn't work for this, because it overlays the result of its scene switch on OBS's single main output. Not what I need to do. I effectively need two independent main outs at the same time, with separate content. The result of one optionally feeds the other (through the V.Cam at the moment, which is also used to feed the manually-produced polished stream to an online meeting, so it has to stay there), but not always.

 

[Fenrir]

The tl;dr is that this is a change in CEF, and likely not something we can even fix even if we were motivated to.

You're also misunderstanding. What we don't support is running multiple copies of OBS that use the same settings directory (i.e. non-portable). We absolutely support running multiple portable instances at the same time.

 

[AaronD]

The tl;dr is that this is a change in CEF, and likely not something we can even fix even if we were motivated to.

What's CEF? Google has lots of clearly unrelated results. This is the only one that seemed relevant to me:

GitHub - chromiumembedded/cef: Chromium Embedded Framework (CEF). A simple framework for embedding Chromium-based browsers in other applications.

Chromium Embedded Framework (CEF). A simple framework for embedding Chromium-based browsers in other applications. - chromiumembedded/cef

github.com

So...if I don't use a browser source or any browser docks, am I okay?

You're also misunderstanding. What we don't support is running multiple copies of OBS that use the same settings directory (i.e. non-portable). We absolutely support running multiple portable instances at the same time.

--profile and --collection aren't enough to use different settings? Seems pretty different to me...

I guess I should also mention that I'm doing this on Ubuntu Studio Linux. I had assumed that all OS's had the same behavior, since they all had the same output from the --help flag. Is that not true? Does the Windows version of OBS have a singleton limitation while the others don't?

 

[Fenrir]

CEF is what runs anything related to a browser in OBS. Browser docks, service integrations, browser sources, etc. etc. So, if you don't use any browser sources then... maybe you're fine from this specific bug? Just understand that it is not a supported configuration, and any issues that might crop up from it are not something we'd look in to or fix. I'm shocked you haven't run in to any kind of data corruption loading multiple live copies from the same settings directory, but, you do you I guess.

The profile and scene collection switches can load different profiles or scene collections, but they all share the same data directory, and systems in OBS are not designed to be safely writing out data to the same locations at the same time, regardless of OS. It is still strongly recommended to set up portable instances for each use case you might have, rather than launching multiple from the same global settings directory.

 

[AaronD]

...not designed to be safely writing out data to the same locations at the same time, regardless of OS.

I wonder if another bug actually saves me from this. My script also shuts things down, by sending the -TERM signal to each of the process ID's that it saved, in reverse order, with similar delays. I tried to find a signal that didn't effectively cause a crash, and couldn't. So I gave up and added the --disable-shutdown-check flag as well.

I would rather not have that flag, and actually do a clean shutdown, but as far as I could tell when I was looking, I can't. So each instance of OBS crashes in turn. Is that the only time it writes to that location? And it doesn't for me because it crashed?

Just understand that it is not a supported configuration, and any issues that might crop up from it are not something we'd look in to or fix.
...
It is still strongly recommended to set up portable instances for each use case you might have, rather than launching multiple from the same global settings directory.

Duly noted. Thanks!

 

[AaronD]

...not designed to be safely writing out data to the same locations at the same time...

Shower thought, literally:
What about adding another command-line option - maybe call it --global or --settings or something like that - that works the same way (to the user at least) as --profile and --collection do. The idea there is to have different native instances read and write to different locations, and thus avoid the problem of multiples clobbering each other.

Would that solve the problem? Or is there something more to it?

It's SO NICE to be able to just install once and then do this in a script:

obs --settings "A" ... &
obs --settings "B" ... &

or on Windows (if I remember the syntax correctly):

cd "C:\path\to\native\OBS"
start "" "obs64.exe" --settings "A" ...
start "" "obs64.exe" --settings "B" ...

 

[prgmitchell]

Shower thought, literally:
What about adding another command-line option - maybe call it --global or --settings or something like that - that works the same way (to the user at least) as --profile and --collection do. The idea there is to have different native instances read and write to different locations, and thus avoid the problem of multiples clobbering each other.

Would that solve the problem? Or is there something more to it?

It's SO NICE to be able to just install once and then do this in a script:

obs --settings "A" ... &
obs --settings "B" ... &

or on Windows (if I remember the syntax correctly):

cd "C:\path\to\native\OBS"
start "" "obs64.exe" --settings "A" ...
start "" "obs64.exe" --settings "B" ...

It seems like you are trying to come up with a more complicated solution to something that is already solved by launching additional instances of OBS in portable mode.

To @Sigma3Wolf I did read your message but Fenrir has elaborated on my suggestion to use portable mode and explanation of why the current behavior is not a bug much more than I ever would've hoped to so I will leave it at that.

 

[OyVey]

I've never used portable mode ever for 2+ years...

It seems like you are trying to come up with a more complicated solution to something that is already solved by launching additional instances of OBS in portable mode.

To @Sigma3Wolf I did read your message but Fenrir has elaborated on my suggestion to use portable mode and explanation of why the current behavior is not a bug much more than I ever would've hoped to so I will leave it at that.

I've never used portable mode for 2+ years, I'm running 4+ streams 24/7 and never had an issue until this past update...

there is clearly an issue and if you're encouraging us to use portable mode the file should be included in the folder, not asking the user to code himself... I didn't have any success in portable mode, so I switched back to the old version.

clearly everything worked fine until the recent update

 

[OyVey]

CEF is what runs anything related to a browser in OBS. Browser docks, service integrations, browser sources, etc. etc. So, if you don't use any browser sources then... maybe you're fine from this specific bug? Just understand that it is not a supported configuration, and any issues that might crop up from it are not something we'd look in to or fix. I'm shocked you haven't run in to any kind of data corruption loading multiple live copies from the same settings directory, but, you do you I guess.

The profile and scene collection switches can load different profiles or scene collections, but they all share the same data directory, and systems in OBS are not designed to be safely writing out data to the same locations at the same time, regardless of OS. It is still strongly recommended to set up portable instances for each use case you might have, rather than launching multiple from the same global settings directory.

everything worked perfectly fine for two years until this recent update, and you're claiming that we're supposed to use portable mode when we've never had to in the first place, never caused any issues, never had any corrupted or mingled files ever.

Just fix the issue, stop claiming it's normal... it isn't normal.

 

[prgmitchell]

I've never used portable mode ever for 2+ years...

I've never used portable mode for 2+ years, I'm running 4+ streams 24/7 and never had an issue until this past update...

there is clearly an issue and if you're encouraging us to use portable mode the file should be included in the folder, not asking the user to code himself... I didn't have any success in portable mode, so I switched back to the old version.

clearly everything worked fine until the recent update

Placing an empty file in a folder is not asking a user to "code himself" and would be required for things to work how you would like them to. You are also welcome to stay on a previous version of OBS if this is working fine for you there.

 

[Sigma3Wolf]

Hmm.. you sta

--multi is, Frankly? A mistake, that we've considered removing. It was added because a single person during a beta test period complained about the new warning dialog. All the option does is suppress the dialog, but I agree it shouldn't be there, and likely never should have been merged.

Launching OBS with a specific scene collection or profile has plenty of uses with a single instance.

Not quite sure I understand. You're saying it's UNSAFE, shouldn't have been added in first place...

yet, I don't see any user here reporting they "ever" had problem using that "feature" that shouldn't have been there.
I sure never had any problem using that removed "feature"

The sugestion to add a flag option is a good idea but it also require different setting to be implemented from a technical point of view on the client side (setting a shortcut with different flag option)

I SUGGEST... the following.
in the old behavior, starting a second instance was detected... showed a warning...
Why not use that feature... when a second instance is launched, make obs switch to a different saving/export directory (that was you said cause problem) -- still showing that warning with precision about where directory will be set.

This would make OBS very much easier to use for non technical user that doesn't know how to use FLAG and command line.

I hope you'll agree to such proposition, in the meanwhile... because I am a good technical user, I'll go learn about how to use Flag and Command line and shortcut in order to use the new version (wich is currently uninstalled)

also.. plz note that as for myself... I'm not using CEF (Browser source) because it is sooooo buggy and unreliable that I use other mean to achieve the same thing. My stream need to be reliable and make the same behavior all the time. it's not time mid stream to start chaging config because CEF crashed ... AGAIN....

I'm sad to learn that basiquely you removed an interesting and usefull "feature" in order to avoid a bug of a bad component.

 

[Sigma3Wolf]

Hmm.. you sta

--multi is, Frankly? A mistake, that we've considered removing. It was added because a single person during a beta test period complained about the new warning dialog. All the option does is suppress the dialog, but I agree it shouldn't be there, and likely never should have been merged.

Launching OBS with a specific scene collection or profile has plenty of uses with a single instance.

ALSO... a very important reason WHY it should be "fixed" another way... is:
Think about user having to SAVE SETTING of ALL their "portable" installation.
They need to go into EVERY instance of portable OBS and export setting.

The current method allow to save settings by only exporting all "Profils" and "Scene collection" from the one instance.
It would be a nighmate for me using the portable method because it will force me to create at least 7 instances. that mean saving settings would require to launch all 7 instance :(

This modification have rather a lot of ramification.

Also... the part I don't understand... you changed something that would not work with a second instance... yet... when this "particular behavior" occur, you don't tell the user about it and the user is now puzzled as to WHY it's not working anymore.

Those that won't find this particular forum blog about it will think OBS is broken (wich in some way is... but that's philosophical debate)

thanks for your excellent work but plz consider other alternative to "fix" that "dangerous" behavior that so many of us are still using.