How to Fix SteamOS Error 4294956486 (Windows and macOS)

Starting off, SteamOS is a Linux-based operating system that runs on a Steam machine gaming platform developed by Valve Corporation. So, the interested Linux users can use SteamOS for major gaming due to its lightweight nature, better graphics support, a list of compatible games, etc. Meanwhile, some of the affected SteamOS users are reporting that they’re encountering SteamOS Error 4294956486 (Windows and macOS) whenever they’re trying to launch games.

As the title suggests, both the Windows and macOS users are experiencing this particular error which is very much irritating. The error message appears like “Failed to start process for Frozen Synapse 2 : OS Error 4294956486”. It also suggests to ‘see the Steam support site for more information’. Now, talking about the reasons for this particular error, there are a couple of reasons like corrupted game files, SteamOS version issue, an outdated Steam client, corrupted Steam installation, Windows Firewall or Defender blocking, NVRAM issue.

How to Fix SteamOS Error 4294956486 (Windows and macOS)

Here we’ve shared all the possible methods to quickly resolve the issue. So, without further ado, let’s get into it.

How to Fix SteamOS Error 4294956486 (Windows and macOS)

1. Force Update Steam Client

It’s quite common and possible that maybe your Steam client becomes outdated and you’re not focusing on it. An outdated program can cause multiple issues like performance degradation, Steam gaming issues, and more.

  • Launch the Steam client > Click on the Steam tab from the upper left corner.
  • Select Check for Steam Client Updates…

If this method doesn’t work for you, try another process below.

  • Close the Steam client properly > Go to the Task Manager by right-clicking on the taskbar.
  • Head over to the Processes tab and close the Steam task.
  • Once done, open File Explorer (This PC) > Navigate to the following path:
C:\Program Files (x86)\Steam

Note: If you’ve installed the Steam client on any other drive or location then head over to the path accordingly.

  • Once you inside the folder, delete every file/folder except for these three items: Steamapps folder, Userdata folder, Steam.exe file.
  • Finally, restart your PC and check for the issue again whether it’s fixed or not.

2. Verify Integrity of Game Files

Needless to say that checking the integrity of the installed game files can ensure whether there are any missing or corrupted game files available or not. If available, the Steam client will automatically fix those issues. Just make sure that your PC is connected to the internet and you’re signed into a proper account.

  • Open the Steam Library by logging into the account
  • You can find a particular game that’s causing the error
  • Now, right-click on the game and click on Properties
  • Select the Local Files tab > Click on Verify Integrity of game files
  • If prompted, allow the process and wait for it to complete.
  • Once done, reboot your PC and run the SteamOS to check for the issue.

3. Create a Shortcut for macOS

If in case, you’re experiencing the game launching issue with the Steam client on macOS then try to create a shortcut for macOS.

  • Launch the Terminal app by double-clicking on it from Applications > Utilities.
  • Once the Terminal app launched, input the following command line that includes the default location:
cd Library/Application/Support/Steam/steamapps/common
  • Now, type Is and hit Enter to see all the installed games. [Make sure to take a note of all the game name exactly]
  • Type the following commands to launch the game which has the issue: [For example, here we assume that XYZ is the game name]
cd "XYZ/"
  • Once all done, restart your Mac and check for the issue again.

Now, you don’t need to do this trick every time. You can simply use the below command to create a shortcut that can launch the particular game for you:

ln -s "/Volumes/*Your Username*/Shared/Steam/steamapps/common/*Gamename*/*Gamename*.app/Contents/MacOS/*Gamename*" ~/Desktop/

Note: Change the Gamename with your actual game title. Similarly, replace the Your Username with the actual username.

Still, the SteamOS Error 4294956486 persists? Don’t worry. Check out the next method.

4. Uninstall & Reinstall Steam


If none of the above methods worked for you, try reinstalling the Steam client on your PC. Sometimes removing and reinstalling the program can fix plenty of temporary cache or glitch that can cause errors.

  • Press Windows + R keys to open up the Run dialog box.
  • Type appwiz.cpl and hit Enter to open up the ‘Programs and Features’.
  • Now, right-click on the Steam and click on ‘Uninstall’.
  • Follow the on-screen instructions to complete the removal process.
  • Once done, restart your computer and download the Steam client again from the official website.
  • Install the client as usual > Sign in to your account and you’re good to go.

5. Disable Third-Party Programs

It’s quite possible that some of the unnecessary third-party programs can conflict with the system performance as well as with the SteamOS games. So, make sure to disable 3rd-party programs while running Steam or playing games on your PC.

Most importantly, you should click on the system tray icon on the taskbar and check which program is unnecessarily running in the background. Just right-click on the particular program icon and either disable it or close it completely.

Additionally, try disabling both the antivirus program and the Firewall (including Defender) to check whether your problem has been resolved or not. If necessary, you uninstall the third-party antivirus software from your computer as well.

6. Reset NVRAM

If the SteamOS Error 4294956486 still appearing on your macOS then try dealing with your NVRAM (Non-Volatile Random-Access Memory) to possibly fix it. To do that:

  • Shut down your Mac > Now, turn it on, and instantly long-press Option + Command + P + R keys for around 20 seconds or so.
  • Now, you can see your macOS is preparing for restart. Don’t release the keys right now.
  • Once you hear two startup tones or beeps, release all keys completely.

Note: If the two beeps sound doesn’t come out, release all keys once the Apple logo disappears for the second time.

  • Once your Mac reboots, launch the Steam client and run the particular game to check whether the problem solves or not.

This method will completely remove the NVRAM cache and your error may have gone now. If none of these workarounds come in handy for you, try contacting Steam support for further assistance. Till then stay tuned for more info. You can comment below for additional queries.

Also Read: How To Fix Steam Disk Write Error

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