[2023] Disk write error?

Please make a thread on our support forum. We need to see your output_log.txt (called player.log on Mac and Linux) to be able to help, which cannot be attached here on Steam.
https://forum.paradoxplaza.com/forum/forums/support-bug-reports.879/

Depending on your operating system the log can be found here:

Windows
\SteamApps\common\Cities_Skylines\Cities_Data\output_log.txt
\CitiesSkylines\Cities_Data\output_log.txt

Mac OS X
~/Library/Logs/Unity/Player.log

Linux
~/.config/unity3d/Colossal Order/Cities: Skylines/Player.log