Same issue, need help

macOS tahoe is last support intel macs, next year support only Apple silicon but Steam is intel applications on macOS 27. Also MacOS 27 is last support rosetta and steam for mac, next year steam dropping support macOS 11 because Chrome 138 is last support for macOS 11

Lmao, okay well this is bad to ear.

At least this is a know issue on Steam, but ear this out, I launched Rimworld before updating and after updating to the beta, and it turn out that Steam isn't able to grab the process at all and same for the game.

Before :
-The game launch, no errors, no bugs or crashes, just the game itself

After :
- The game might crash sometimes, we need to reinstall Rimworld from the beginning but settings will be recovered right after.
- The game tell us that It cannot connect with steam, he tell us to check if we doesn't edit the steam_appid.txt file inside it, and if we don't run. the process in administrator or some kind of this, it also tell us to reboot the computer and check again (which obviously don't change anything here)


Also one things to know, is that the first time you've install the update, there's bunch of popup telling us to cord some privilege to apps we already say (Yes this app can access the whole disk)

My thought is when we install the Beta macOS 26 Tahoe, it does some kind of reset the preferences of permission for each apps on our system, including apps from Steam that use other hide apps that can make a path/connexion between Steam Launcher and the App/Games we launch thourgh.
So the game is just like launching outside of Steam, (double clicking on the game in SteamLibrary and launching it without steam) and tell us he cannot talk to that layer of connexion to ask Steam if the player is online, banned or something else.
So steam, waits just like on linux when a game froze at the beginning, instead of telling us that we can start the game again, it froze on the launching/playing button and wait for a response for a process that can't do anything.


I try right after this post to reinstall steam entirely just to check if it's correct but I might be wrong.
Cia,
WiBlum

Okay, after doing this, telling Apple Quarantine to let Steam do what he want to do.
Telling in the settings to let Steam on the Whole disk, Mic, Bluetooth, and other, it won't change anything ..
Sorry and have a good day

Yeah gaming in general seems broken at the moment, steam has the problems as mentioned but now games are crashing very frequently. I usually install a new mac os as soon as the beta is available, but cant remember them being this buggy.

At least Rimworld works fine (mods also) without steam being launched

Apparently it's global, the macOS update broke quite a lot of apps, here is a list I found 2 days ago :
https://forums.macrumors.com/threads/macos-26-beta-1-working-and-non-working-apps-thread.2458467/

Also I wonder why does it broke.

This might help a bit also it is from official apple feedback (dev Release notes) :
You might experience layout issues when going full screen with certain apps on a Mac. (151266898)

For supported game controllers, pressing the Home button once opens the Game Overlay. Set preferredSystemGestureState to receive additional Home button press events. (137780853)


[...]

Metal 4 is now supported. See Metal for additional details. (113781091)
If you're using Metal 4 command encoders, you should add render and compute pipelines that support indirect command buffers to your residency sets. The Metal device driver currently does not enforce this requirement. (145066238)
Metal Shader Validation might not work with shaders that use Metal Performance Primitives. (149263281)
Metal Shader Validation might not work with Metal 4 ray tracing pipelines. (152520367)
Workaround: Selectively disable Shader Validation for pipelines using ray tracing. See documentation.

Denoised temporal upscaling for MTL4CommandBuffer's MTL4FXTemporalDenoisedScaler does not work. (146436460)
Temporal upscaling for MTL4CommandBuffer's MTL4FXTemporalScaler does not work. (146436741)

Algorithms DES, 3DES, SHA1-96 and SHA1-160 as well as Diffie-Hellman groups less than 14 are no longer supported for IKEv2 VPNs. (148767790)

[...]


The Swift compiler might crash when building a project that initializes a UISymbolContentTransition. (150858005)

A LOT (not pasting this here)
If Default Actor Isolation is set to MainActor, @Animatable macro emits concurrency warnings in Swift 5 language mode and does not compile in Swift 6 language mode. (152524435)
Workaround: Use Swift 5 language mode or set Default Actor Isolation to nonisolated in project's build settings.
Text concatenation using the + operator is deprecated because it makes it hard to create localized strings that are correct across all languages. Use Text interpolation instead. See documentation on Text for more info on how to produce localized strings. (128144043)


And here is the source : https://developer.apple.com/documentation/macos-release-notes/macos-26-release-notes

In conclusion, you'll probably have those issues :
- With most games, including Whisky (Wine) games that runs in fullscreen
- Issue with native games that use MethalFX
- And a network extension that is deprecated for algorithms (list above)

But, we got a new Gaming Overlay, that's cool but we probably won't be able to show it in most games that had issues with fullscreen ou crash :/

I hope that a patch for theses known issues will come near this week, probably not but since it's the very first 3 days after uploading macOS 26 Tahoe, it seems normal just like iOS 18 with most apps (like Nintendo apps or some other games that just refuse to start and crash instantly) and the patch come both from devs of those apps and patch from Apple.

It still is a dev build, so that's okay.

I ask for support from Valve, they probably can do something for it.
i let you know if I got an update on it

I wanted to add this to the thread as well. American Truck Simulator is no longer launching. The Steam client app indicates that it’s currently running, but I’ve confirmed through the Activity Monitor that the game itself isn’t actually running. I’ve already submitted feedback to the Feedback Assistant app on macOS.

Description:
When launching a game (e.g., American Truck Simulator) on the Steam app for macOS Tahoe, the client says the game is "Running," but the game itself never starts. The application window does not appear, and it isn't listed in the Dock or Activity Monitor. The only way to resolve the "Running" status is to press the "Stop" button within Steam.

Steps to reproduce:
1. Open the Steam client on macOS Tahoe developer beta.
2. Go to the Library and select a game.
3. Click "Play".
4. Observe that Steam's status for the game changes to "Running".
5. Confirm that the game application never actually launches.

Update to Steam Arm beta it will fix the issue.

Nope, even updating to Steam Beta it won't fix the issue for other native games like Rimworld

Valve respond, they just basically redirect me to this page :
https://steamhost.cn/steamcommunity_com/discussions/forum/10/

Which is the same page as here ...


I ask them to give more détails of what's going on.
Bye ;)

Okay, nah sorry, we have to replace the current Steam app by the new one on "Download steam" page section, then go the settings, interface, and make sure Steam Beta Update is check on

This fixed the whole thing
Have a nice day y'all bye

yea tha Mac
OS26 Tahoe cooked my ♥♥♥♥