ValueError: Birch threshold must be positive

ValueError: Birch threshold must be > 0

$ python -c "from sklearn.cluster import Birch; Birch(threshold=0).fit([[0,0],[1,1]])"
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ValueError: threshold must be > 0

Why this happens

threshold cannot be zero or negative.

Fix

Use a small positive value like 0.5.

Wrong code

from sklearn.cluster import Birch
Birch(threshold=0)

Fixed code

from sklearn.cluster import Birch
Birch(threshold=0.5)