Cities: Skylines (Steam) - Game won't load (Mac OS X 11.4)


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Jun 10, 2020
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Describe your issue
Game won't load (Mac OS X 11.4)

What is your game version?

What expansions do you have installed?

What mods are you using?
Several. New game will load using -noWorkshop option.

Please explain your issue is in as much detail as possible.
Recently updated to the 2021.6 launcher after not being able to open the game in an older launcher. Game crashes and causes a full system reboot after getting to 98% loading. This happens whether I start a new game or attempt to load a saved game. I read the log and 'Fatal Assertion Failed: Stalled cross-thread pipe' pops up toward the bottom.

I have already done new installs of both the Steam client and Cities: Skylines. I am also in the process of downsizing my asset list. Started with about 5,600 and am currently down to approximately 4,900.

Can you replicate the issue? If yes, please explain how you did it.
Yes. I've started a new game and have loaded a save. The game always crashes.

Attachments File(s) attached


  • Player.log
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Hmm, since you are subscribed to huge number of assets, and I noticed that the game created a lot of web requests to steam (fetch info about subscribed assets and mods) I suggest trying LessSteam mod.
It will reduce number of web requests, speed up loading and hopefully fix game crash issue.


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Yes, you have over 4,000 items subscribed trying to fit in 16gb of system memory. Depending on asset complexity you can expect to comfortably load between 1-2,000 perhaps. Please unsubscribe from any mods and assets you don't actually need or use - they all consume memory all the time, even when not in use in the current city.

And exit every other app you can before starting the game.

Good luck with that!