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
1032694511,I_kwDOAMm_X849jarv,5882,"Opening remote file with OpenDAP protocol returns ""_FillValue type mismatch"" error",42075938,closed,0,,,9,2021-10-21T16:27:17Z,2021-10-29T09:30:40Z,2021-10-29T09:30:40Z,NONE,,,,"**What happened**:
When trying to open a remote file with OpenDAP protocol, I receive the error `Not a valid data type or _FillValue type mismatch: b'http://opendap.tudelft.nl/thredds/dodsC/IDRA/2019/10/01/IDRA_2019-10-01_11-00_raw_data.nc'`.

**What you expected to happen**:
I expect the file to be opened without having to add the string `'#fillmismatch'` to the file's URL (see example below).
I am not specifying any `engine` in the method `open_dataset()`. However, if I specify `'pydap'`, I receive a different type of error: `unrecognized engine pydap must be one of: ['netcdf4', 'scipy', 'store']`; although I have pydap 3.2.2 installed and ran `!pip install xarray[complete]`

**Minimal Complete Verifiable Example**:

```python
url = 'http://opendap.tudelft.nl/thredds/dodsC/IDRA/2019/10/01/IDRA_2019-10-01_11-00_raw_data.nc'
ds = xr.open_dataset(url+'#fillmismatch')
```

**Anything else we need to know?**:
Unidata/netcdf4-python#929

**Environment**:
- Ubuntu 20.04
- [JupyerLab running on Docker.](https://hub.docker.com/repository/docker/saveriogzz/jupyterdatascience)


<details><summary>Output of <tt>xr.show_versions()</tt></summary>

<!-- Paste the output here xr.show_versions() here -->
INSTALLED VERSIONS
------------------
commit: None
python: 3.7.4 (default, Aug 13 2019, 20:35:49) 
[GCC 7.3.0]
python-bits: 64
OS: Linux
OS-release: 5.4.0-88-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.UTF-8
LOCALE: ('en_US', 'UTF-8')
libhdf5: 1.12.0
libnetcdf: 4.7.4

xarray: 0.18.2
pandas: 1.2.4
numpy: 1.20.3
scipy: 1.6.3
netCDF4: 1.5.6
pydap: installed
h5netcdf: 0.11.0
h5py: 3.5.0
Nio: None
zarr: 2.10.2
cftime: 1.5.0
nc_time_axis: 1.3.1
PseudoNetCDF: None
rasterio: 1.2.10
cfgrib: None
iris: None
bottleneck: 1.3.2
dask: 2021.05.0
distributed: 2021.05.0
matplotlib: 3.4.2
cartopy: None
seaborn: 0.11.2
numbagg: 0.2.1
pint: None
setuptools: 45.1.0.post20200119
pip: 21.1.2
conda: 4.7.12
pytest: 6.2.4
IPython: 7.11.1
sphinx: None


</details>
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