[2021] Can't save game, please help!

Let's start by seeing if it's mod related. Add the launch options -noWorkshop and -disableMods to Steam, then start the game and start a new map. Test to see if you can save it.

How To Set Launch Options

• Right-click on the game title under the Library in Steam and select Properties.
  
• Under the General tab click the Set launch options... button.
  
• Enter the launch options you wish to apply (be sure to separate each code with a space) and click OK. Should look like this:
  -noWorkshop -disableMods
• Close the game's Properties window and launch the game.

If it doesn't save with the launch options in place, definitely also make sure to whitelist cities.exe in your antivirus app. It may be blocking Cities from creating a savefile.

Originally posted by Accept Cookies: It didn't save with the launch options in place so I'll look into my antivirus app, thanks Avanya.

No problem. Fingers crossed that'll do the trick. But if it doesn't, then the best place to get help would be the official support forums. :)

https://forum.paradoxplaza.com/forum/forums/support-bug-reports.879/