No more bootstrap providers remain?

I’m developing a multi threaded rails application and see this error in production quite often:
No more bootstrap providers remain (error=0x17)

There doesn’t seem to be any issue with couchbase itself and I don’t need to have too many concurrent requests before this issue starts appearing.

So I was wondering what the error means and how I can prevent these errors before the application sees any real workloads?
I looked through the libcouchbase code and it seemed to be related to connecting to servers? Am I maxing out connections from the client?