issues: 502720385

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association active_lock_reason draft pull_request body reactions performed_via_github_app state_reason repo type
502720385 MDU6SXNzdWU1MDI3MjAzODU= 3374 Key error in to_netcdf 6943441 closed 0     5 2019-10-04T16:04:30Z 2023-03-14T21:14:33Z 2023-03-14T21:14:33Z NONE      

MCVE Code Sample

```python import xarray as xr

p = range(10) ds = xr.Dataset({'precip': (['time'], p)}, coords={'time': range(10)}) ds.attrs['Conventions'] = ['COARDS', 'GrADS'] ds.to_netcdf('a.nc') ```

Expected Output

Saves data to a.nc without error

Problem Description

In version 0.12.1 this works without error. In 0.12.2 it throws an error:

File "xarray_error.py", line 6, in <module> ds.to_netcdf('a.nc') File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\xarray\core\dataset.py", line 1365, in to_netcdf compute=compute) File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\xarray\backends\api.py", line 900, in to_netcdf store.close() File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\xarray\backends\scipy_.py", line 226, in close self._manager.close() File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\xarray\backends\file_manager.py", line 188, in close file.close() File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\scipy\io\netcdf.py", line 299, in close self.flush() File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\scipy\io\netcdf.py", line 409, in flush self._write() File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\scipy\io\netcdf.py", line 420, in _write self._write_gatt_array() File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\scipy\io\netcdf.py", line 442, in _write_gatt_array self._write_att_array(self._attributes) File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\scipy\io\netcdf.py", line 450, in _write_att_array self._write_att_values(values) File "C:\Users\jsadler\AppData\Local\Continuum\anaconda3\envs\nwm\lib\site-packages\scipy\io\netcdf.py", line 562, in _write_att_values nc_type = REVERSE[values.dtype.char, values.dtype.itemsize] KeyError: ('U', 24)

If instead the attribute is saved as as string instead of a list, it works: ```python import xarray as xr

p = range(10) ds = xr.Dataset({'precip': (['time'], p)}, coords={'time': range(10)}) ds.attrs['Conventions'] = "['COARDS', 'GrADS']" ds.to_netcdf('a.nc') ```

Output of xr.show_versions()

INSTALLED VERSIONS ------------------ commit: None python: 3.7.4 (default, Aug 9 2019, 18:34:13) [MSC v.1915 64 bit (AMD64)] python-bits: 64 OS: Windows OS-release: 10 machine: AMD64 processor: Intel64 Family 6 Model 158 Stepping 10, GenuineIntel byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: None.None libhdf5: None libnetcdf: None xarray: 0.12.2 pandas: 0.25.1 numpy: 1.17.1 scipy: 1.3.1 netCDF4: None pydap: installed h5netcdf: None h5py: None Nio: None zarr: 2.3.2 cftime: None nc_time_axis: None PseudonetCDF: None rasterio: None cfgrib: None iris: None bottleneck: None dask: 2.3.0 distributed: 2.5.1 matplotlib: 3.1.1 cartopy: None seaborn: None numbagg: None setuptools: 41.2.0 pip: 19.2.3 conda: None pytest: 5.1.2 IPython: 7.8.0 sphinx: None 
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