[2020] Terraform tool NOT WORKING

Try unsubscribing from Extra Landscaping Tools, waiting a moment for Steam to remove the files, then subscribe to the mod again. Let it download and then try to start the game again.

Hmm, that sounds like a new error. Try verifying game files by going to the library in Steam, right clicking on Cities: Skylines, select Properties, go to the tab named Local Files and click on Verify Integrity of Game Files. Let Steam do its thing and start the game again.

If you have errors again, upload the log again and drop a new link, so we can see if something has changed.

Yeah, it's very likely mod related. Not sure what's causing it though. :/

I noticed you have both Disable Zone Check and Plop the Growables. These mods are incompatible and break when used together. It isn't related to this problem, but you should pick one and remove the other.

You also don't nee Tree Brush when using Extra Landscaping Tools and Forest Brush.

For the problem you're having, I suggest unsubscribing both Extra Landscaping Tools and Surface Painter, then test if the default terraforming works. If the problem is gone, something is messing with ELT. If it's still there, it's a different mod breaking things (upload a new log if that's the case).