54234 deprecated the case of skipna=False and any NA value, but for consistency with Series/DataFrame versions, we also want the case of skipna=True with all NA values in a group to also raise. E.g. this should raise a ValueError

df = pd.DataFrame({'a': [1, 1, 2], 'b': np.nan})
gb = df.groupby("a")
print(gb.idxmin())

Comment From: jbrockmendel

Make this a breaking change in 3.0? Could do a full deprecation cycle, but the inconsistency will be annoying in the interim.

Comment From: rhshadrach

That sounds good to me.

Comment From: jbrockmendel

Did we ever do this?