Guten Tag,
Hey, I was looking for help on a netlify functions error, I found this:
I was having the same issue. 
BUT, I fixed it!
I cant reply to that guy or post in that thread for some reason, but have him modify his netlify.toml like this:
[dev]
functions = “netlify/functions/”
publish = “src/”
instead of this:
[dev]
publish = “src/”
The key here is that “netlify” part. Take it out and you get the same issue he had: couldnt reach the function from localhost.
#wont work:
[dev]
functions = “functions/”
Have a good day!
-Jason