I’ve just encountered the same issue: added a deployment section and my next build failed with that same error message. Did you manage to figure out what the issue is? That error message is useless.
Edit: In my case, I had a single space before the “—” at the start of my yaml file. Removing that space fixed the issue for me.
I had an extra colon in my test config sections in the circle.yml file.
test:
override:
- tox:
Removing that fixed the issues
test:
override:
- tox
Hop this helps, but in most cases it will just be a issue with your circle.yml structure