html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/2436#issuecomment-610073334,https://api.github.com/repos/pydata/xarray/issues/2436,610073334,MDEyOklzc3VlQ29tbWVudDYxMDA3MzMzNA==,14808389,2020-04-06T22:38:30Z,2020-04-06T22:38:30Z,MEMBER,I removed it since it doesn't change anything.,"{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,363299007
https://github.com/pydata/xarray/issues/2436#issuecomment-610053703,https://api.github.com/repos/pydata/xarray/issues/2436,610053703,MDEyOklzc3VlQ29tbWVudDYxMDA1MzcwMw==,14808389,2020-04-06T21:45:47Z,2020-04-06T22:03:08Z,MEMBER,"unfortunately, `numpy` does not allow us to put `cftime` object into dtypes (yet!), so `ds.time.values` is a `numpy.ndarray` with dtype `object`, containing `cftime` objects. To make the code work, use it with `ds.time.values[0]`. Of course, that won't help if the array contains objects of more than one type.

```python
>>> import cftime
>>> isinstance(ds.time.values[0], cftime.DatetimeNoLeap)
True
>>> type(ds.time.values[0])
<class 'cftime._cftime.DatetimeNoLeap'>
```

In #3498, the original proposal was to name the new kwarg `master_file`, but later it was renamed to `attrs_file`. If `l_f` is a list of file paths, you used it correctly.

Before trying to help with debugging your issue: could you post the output of `xr.show_versions()`? That would help narrowing down on whether it's a dependency issue or a bug in `xarray`.

Also, could you try to demonstrate your issue using a synthetic example? I've been trying to reproduce it with:
```python
In [14]: units = 'days since 2000-02-25' 
    ...: times = cftime.num2date(np.arange(7), units=units, calendar='365_day') 
    ...: for x in range(5): 
    ...:     ds = xr.DataArray( 
    ...:         np.arange(x, 7 + x).reshape(7, 1), 
    ...:         coords={""time"": times, ""x"": [x]}, 
    ...:         dims=['time', ""x""], 
    ...:         name='a', 
    ...:     ).to_dataset() 
    ...:     ds.to_netcdf(f'data-noleap{x}.nc') 
    ...: paths = sorted(glob.glob(""data-noleap*.nc"")) 
    ...: with xr.open_mfdataset(paths, combine=""by_coords"") as ds: 
    ...:     print(ds.time.encoding) 
    ...:
{'zlib': False, 'shuffle': False, 'complevel': 0, 'fletcher32': False, 'contiguous': True, 'chunksizes': None, 'source': '.../data-noleap0.nc', 'original_shape': (7,), 'dtype': dtype('int64'), 'units': 'days since 2000-02-25 00:00:00.000000', 'calendar': 'noleap'}
```","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,363299007