To easily find the folder mentioned in the error, right click your game in the Steam library, select Properties, go to the Local Files tab and select Browse local files.

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

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

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

You can upload it somewhere and link to it, then I'll have a look. Or you can make a post on the official support forums here: https://forum.paradoxplaza.com/forum/forums/support-bug-reports.879/As we can't attach files here on Steam, you will need to upload the file somewhere else. Here's a few sites you can upload it to, which do not require you to sign up first:https://uploadfiles.io/ - free, no sign-up, can handle large log files
https://paste.ee/ - fast, no sign-up required (some log files will be too large for it though)
https://zerobin.net/ - bit clunky, but can handle huge files, no sign-up required

Originally posted by jamesrh59: Non of the above. I purchased the game through STEAM and by consumer law they should put it right. My laptop has 16GB of memory and 1TB SSD. Ryzen 7 with Geforce RTX 260. All my other games play flawlessly so no I don't think it is a limitation of my laptop. I f you bought something from a retailer and your goods did not perform as they should would you go to the manufacturer or the company who sold it to you to put it right??? I sent the problem some time ago to Paradox and they reffered me back to Steam. So I am going round in circles with this and I would expect steam to sort it out or give a refund which neither seems to be happening.

If you can post your log somewhere, I'd be happy to take a look and see what's going on. But without a look at your game's log, I'd just be guessing. It's easier for me to help you with a log, so I don't have you try a bunch of different things, which aren't relevant to your problem. :)

See my previous response for where to find it and some file sharing sites you can use. Any cloud drive (like Google Drive, Dropbox, OneDrive, iCloud etc) will also work.

Wrong file I'm afraid. That's one called GameOverlayUI.exe.log.last - I need the output_log.txt (called player.log on Mac and Linux).

Then the file I need is called output_log.txtIf your Steam is installed in the default location, it will be found here:
C:\Program Files (x86)\Steam\steamapps\common\Cities_Skylines\Cities_Data