Black hole when loading save.

"sim dll not found" - try to verify your game files via steam; that file seems to be missing

 

did you use that "multi threaded sim" mod that does some freaky things to those files?

Edited October 18, 2025 by SGT_Imalas

When in doubt...blame 

39 minutes ago, SGT_Imalas said:

"sim dll not found" - try to verify your game files via steam; that file seems to be missing

 

did you use that "multi threaded sim" mod that does some freaky things to those files?

I did the "verify game files" via steam, but omitted writing it on account of later reinstalling the game altogether. That mod does make me curious but I've never tried it.

23 minutes ago, Tigin said:

When in doubt...blame 

I blame lack of "remembering you have to support linux too" instead. System works fine.

ONI runs better on Linux™

When was the last time you were able to play ONI? Have you installed Steam via flatpak or Valve's official installer?

Does this file exist?

Fallback handler could not load library /home/user1/.steam/debian-installation/steamapps/common/OxygenNotIncluded/OxygenNotIncluded_Data/MonoBleedingEdge/x86_64/libSimDLL.so

 

There's another Linux user with the same issue. 

 

3 hours ago, EricKlei said:

When was the last time you were able to play ONI? Have you installed Steam via flatpak or Valve's official installer?

Although I will admit to taking a short break from ONI I did play prior to the latest update (693461)

I don't use flatpak, snap or any other variation on the package management craze that came from that idea. So that just leaves the installation via good 'ol steam.

3 hours ago, EricKlei said:

Does this file exist?

Fallback handler could not load library /home/user1/.steam/debian-installation/steamapps/common/OxygenNotIncluded/OxygenNotIncluded_Data/MonoBleedingEdge/x86_64/libSimDLL.so

 

Parsing the directory tree to that folder we get that the file you're looking for isn't present:

 

 

 

This is the state of the folder even after verifying files via steam and even after a full game reinstall (again, via steam/valve's official installer).

 

I await further queries & instructions. I'll also take advantage of this opportunity to say we could use more ONI emojis, just sayin'...

 

 

What about in OxygenNotIncluded_Data\Plugins? Here's what you should have in that folder.

Edit: What distro are you using? Your log says Linux 5.15 Steam Runtime 2 64bit.

2 hours ago, EricKlei said:

What about in OxygenNotIncluded_Data\Plugins? Here's what you should have in that folder.

 

Here's some fun files I found:

 

 

2 hours ago, EricKlei said:

Edit: What distro are you using? Your log says Linux 5.15 Steam Runtime 2 64bit.

The plot thickens, what has changed since? I mean, I haven't updated my system to a newer distro in quite a while now.

I know I should bring the system up from 20.04.6 to the latest LTS, but that would trigger a "maintenance day" where I reinstall-update the OS from scratch and might even change the motherboard on this box just because.

Time to start playing with some symlinks.

Edit:

I temporarily copied the contents from the Plugins folder into the x86_64 folder to test if the game would even detect libSimDLL.so
No such luck.

 

When I look at the error list in player.log this is the first and only line that pops starkly into view (after the text block of "fallback handler" which also references "SimDLL"):

[01:31:42.059] [1] [ERROR] SaveLoader ~~~!System.DllNotFoundException: SimDLL assembly:<unknown assembly> type:<unknown type> member:(null)

I feel obligated to ask "which file is SimDLL?" without the rest of the file name we were looking for... (as in "libSimDLL.so")

Edited October 21, 2025 by JRup
Added info. No positive result.

We recently upgraded our build machine which creates the SimDLL (libSimDll.so is the file) from Ubuntu 20.04 to 24.04. The October 8th hotfix was the first public release made on it. Certain libraries such as glibc need a more recent version so updating Ubuntu will very likely fix it.

 

Oh well, "maintenance day" is "more imminent" given this revelation...

As much as I'd like to push for a detailed list of what may "need updating" I'm not that willing to dive into that mire of "dependencies to look into".

I could recommend verifying the minimum OS requirement on the game's page as it may not apply anymore.

Yes, ONI has been with us for quite a while now.

I will report on my findings after the system update is done, but that will take some extra scheduling for later (this week, hopefully).

We're still investigating options but the issue appears to be related to upgrading to glibc 2.38+ which is not backwards compatible. This is a core system library so I wouldn't recommend trying to upgrade it by itself. Once we determine the minimum requirements we will update the Steam page accordingly.

On 10/21/2025 at 11:19 PM, EricKlei said:

We're still investigating options but the issue appears to be related to upgrading to glibc 2.38+ which is not backwards compatible.

I shall soon dive into the public testing branch that's got this one fixed. Thank you very much!

Changed Status to Fixed

Thanks for confirming it's been fixed. The SimDLL is now being built in and uses the the Steam Linux Runtime 3.0 (sniper) so going forward it should be more compatible.