cdf_to_xarray to_netcdf fails with ValueError

[berniegsfc]

The following code:

from cdflib.xarray import cdf_to_xarray,xarray_to_cdf
import xarray as xr

# https://cdaweb.gsfc.nasa.gov/pub/data/ace/mag/level_2_cdaweb/mfi_h0/1997/ac_h0_mfi_19970902_v04.cdf
filename = 'ac_h0_mfi_19970902_v04.cdf'

data = cdf_to_xarray(filename)

#xarray_to_cdf(data, 'data.cdf')

data.to_netcdf('data.nc')

fails with

ValueError: failed to prevent overwriting existing key units in attrs on variable 'Epoch'. This is probably an encoding field used by xarray to describe how a variable is serialized. To proceed, remove this key from the variable's attributes manually.

Is this a problem with the xarray.Dataset produced by cdf_to_xarray or a problem with xarray.Dataset.to_netcdf()?

[berniegsfc]

I've tried different versions of cdflib, xarray, and python and it fails the same in all. But for the record, the last test was with

• cdflib 1.3.1
• xarray 2024.7.0
• python 3.10.5