import pandas as pd
df = pd.DataFrame(columns=['A', 'B'])
df['C'] = pd.to_numeric(df['A'])

I am not sure what the correct behavior should be here but it definitely should not crash the kernel.

INSTALLED VERSIONS ------------------ commit: None python: 3.5.2.final.0 python-bits: 64 OS: Windows OS-release: 8.1 machine: AMD64 processor: Intel64 Family 6 Model 63 Stepping 2, GenuineIntel byteorder: little LC_ALL: None LANG: None LOCALE: None.None pandas: 0.19.2 nose: 1.3.7 pip: 8.1.2 setuptools: 27.2.0 Cython: 0.24.1 numpy: 1.11.3 scipy: 0.18.1 statsmodels: 0.6.1 xarray: None IPython: 5.1.0 sphinx: 1.4.6 patsy: 0.4.1 dateutil: 2.5.3 pytz: 2016.6.1 blosc: None bottleneck: 1.1.0 tables: 3.2.2 numexpr: 2.6.2 matplotlib: 1.5.3 openpyxl: 2.3.2 xlrd: 1.0.0 xlwt: 1.1.2 xlsxwriter: 0.9.3 lxml: 3.6.4 bs4: 4.5.1 html5lib: None httplib2: None apiclient: None sqlalchemy: 1.0.13 pymysql: 0.7.9.None psycopg2: None jinja2: 2.8 boto: 2.42.0 pandas_datareader: None

Comment From: jreback

you have an older version, this is all fixed on 0.20.3 I think and certainly on 0.21.0