# Buggy code
def save_dataset(
    self, dataset, filename=None, fill_value=None, compute=True, base_dir=None, **kwargs
):
    LOG.debug("Starting in mitiff save_dataset ... ")

    def _delayed_create(create_opts, dataset):
        LOG.debug("create_opts: %s", create_opts)
        try:
            if "platform_name" not in kwargs:
                kwargs["platform_name"] = dataset.attrs["platform_name"]
            if "name" not in kwargs:
                kwargs["name"] = dataset.attrs["name"]
            if "start_time" not in kwargs:
                kwargs["start_time"] = dataset.attrs["start_time"]
            if "sensor" not in kwargs:
                kwargs["sensor"] = dataset.attrs["sensor"]

            try:
                self.mitiff_config[kwargs["sensor"]] = dataset.attrs[
                    "metadata_requirements"
                ]["config"]
                self.channel_order[kwargs["sensor"]] = dataset.attrs[
                    "metadata_requirements"
                ]["order"]
                self.file_pattern = dataset.attrs["metadata_requirements"][
                    "file_pattern"
                ]
            except KeyError as ke:
                LOG.warning(
                    "Something went wrong with assigning to various dicts: %s", ke
                )

            try:
                self.translate_channel_name[kwargs["sensor"]] = dataset.attrs[
                    "metadata_requirements"
                ]["translate"]
            except KeyError as ke:
                LOG.warning("Something went wrong with assigning to translate: %s", ke)

            image_description = self._make_image_description(dataset, **kwargs)
            LOG.debug("File pattern %s", self.file_pattern)
            self.filename_parser = self.create_filename_parser(create_opts)
            gen_filename = filename or self.get_filename(**kwargs)
            LOG.info("Saving mitiff to: %s ...", gen_filename)
            self._save_datasets_as_mitiff(
                dataset, image_description, gen_filename, **kwargs
            )
        except:
            raise

    save_dir = "./"
    if "mitiff_dir" in kwargs:
        save_dir = kwargs["mitiff_dir"]
    elif "base_dir" in kwargs:
        save_dir = kwargs["base_dir"]
    elif base_dir:
        save_dir = base_dir
    else:
        LOG.warning("Unset save_dir. Use: %s", save_dir)
    create_opts = save_dir
    delayed = dask.delayed(_delayed_create)(create_opts, dataset)

    if compute:
        return delayed.compute()
    return delayed


# Traceback (KeyError)
scn.save_dataset('natural', writer='mitiff', filename='/tmp/mitiff.tif')
[DEBUG: 2018-07-16 12:29:43 : satpy.writers] Reading ['/home/lahtinep/Software/miniconda3/lib/python3.6/site-packages/satpy-0.9.1a0.dev0-py3.6.egg/satpy/etc/writers/mitiff.yaml']
[DEBUG: 2018-07-16 12:29:43 : satpy.writers.mitiff] Starting in mitiff save_dataset ...
[WARNING: 2018-07-16 12:29:43 : satpy.writers.mitiff] Unset save_dir. Use: ./
/home/lahtinep/Software/miniconda3/lib/python3.6/site-packages/pyresample/kd_tree.py:924: RuntimeWarning: invalid value encountered in sqrt
mask=mask)
[DEBUG: 2018-07-16 12:29:45 : satpy.writers.mitiff] create_opts: ./
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-48-762780f9f91a> in <module>()
----> 1 lcl.save_dataset('natural', writer='mitiff', filename='/tmp/mitiff.tif')

~/Software/miniconda3/lib/python3.6/site-packages/satpy-0.9.1a0.dev0-py3.6.egg/satpy/scene.py in save_dataset(self, dataset_id, filename, writer, overlay, compute, **kwargs)
1008         return writer.save_dataset(self[dataset_id], filename=filename,
1009                                    overlay=overlay, compute=compute,
-> 1010                                    **save_kwargs)
1011
1012     def save_datasets(self, writer="geotiff", datasets=None, compute=True,

~/Software/miniconda3/lib/python3.6/site-packages/satpy-0.9.1a0.dev0-py3.6.egg/satpy/writers/mitiff.py in save_dataset(self, dataset, filename, fill_value, compute, base_dir, **kwargs)
116
117         if compute:
--> 118             return delayed.compute()
119         return delayed
120

~/Software/miniconda3/lib/python3.6/site-packages/dask/base.py in compute(self, **kwargs)
154         dask.base.compute
155         """
--> 156         (result,) = compute(self, traverse=False, **kwargs)
157         return result
158

~/Software/miniconda3/lib/python3.6/site-packages/dask/base.py in compute(*args, **kwargs)
400     keys = [x.__dask_keys__() for x in collections]
401     postcomputes = [x.__dask_postcompute__() for x in collections]
--> 402     results = schedule(dsk, keys, **kwargs)
403     return repack([f(r, *a) for r, (f, a) in zip(results, postcomputes)])
404

~/Software/miniconda3/lib/python3.6/site-packages/dask/threaded.py in get(dsk, result, cache, num_workers, **kwargs)
73     results = get_async(pool.apply_async, len(pool._pool), dsk, result,
74                         cache=cache, get_id=_thread_get_id,
---> 75                         pack_exception=pack_exception, **kwargs)
76
77     # Cleanup pools associated to dead threads

~/Software/miniconda3/lib/python3.6/site-packages/dask/local.py in get_async(apply_async, num_workers, dsk, result, cache, get_id, rerun_exceptions_locally, pack_exception, raise_exception, callbacks, dumps, loads, **kwargs)
519                         _execute_task(task, data)  # Re-execute locally
520                     else:
--> 521                         raise_exception(exc, tb)
522                 res, worker_id = loads(res_info)
523                 state['cache'][key] = res

~/Software/miniconda3/lib/python3.6/site-packages/dask/compatibility.py in reraise(exc, tb)
67         if exc.__traceback__ is not tb:
68             raise exc.with_traceback(tb)
---> 69         raise exc
70
71 else:

~/Software/miniconda3/lib/python3.6/site-packages/dask/local.py in execute_task(key, task_info, dumps, loads, get_id, pack_exception)
288     try:
289         task, data = loads(task_info)
--> 290         result = _execute_task(task, data)
291         id = get_id()
292         result = dumps((result, id))

~/Software/miniconda3/lib/python3.6/site-packages/dask/local.py in _execute_task(arg, cache, dsk)
269         func, args = arg[0], arg[1:]
270         args2 = [_execute_task(a, cache) for a in args]
--> 271         return func(*args2)
272     elif not ishashable(arg):
273         return arg

~/Software/miniconda3/lib/python3.6/site-packages/satpy-0.9.1a0.dev0-py3.6.egg/satpy/writers/mitiff.py in _delayed_create(create_opts, dataset)
76                     kwargs['name'] = dataset.attrs['name']
77                 if 'start_time' not in kwargs:
---> 78                     kwargs['start_time'] = dataset.attrs['start_time']
79                 if 'sensor' not in kwargs:
80                     kwargs['sensor'] = dataset.attrs['sensor']

KeyError: 'start_time'

# Fixed code
def save_dataset(self, dataset, filename=None, fill_value=None, compute=True, **kwargs):
    LOG.debug("Starting in mitiff save_dataset ... ")

    def _delayed_create(create_opts, dataset):
        try:
            if "platform_name" not in kwargs:
                kwargs["platform_name"] = dataset.attrs["platform_name"]
            if "name" not in kwargs:
                kwargs["name"] = dataset.attrs["name"]
            if "start_time" not in kwargs:
                kwargs["start_time"] = dataset.attrs["start_time"]
            if "sensor" not in kwargs:
                kwargs["sensor"] = dataset.attrs["sensor"]

            try:
                self.mitiff_config[kwargs["sensor"]] = dataset.attrs[
                    "metadata_requirements"
                ]["config"]
                self.channel_order[kwargs["sensor"]] = dataset.attrs[
                    "metadata_requirements"
                ]["order"]
                self.file_pattern = dataset.attrs["metadata_requirements"][
                    "file_pattern"
                ]
            except KeyError:
                # For some mitiff products this info is needed, for others not.
                # If needed you should know how to fix this
                pass

            try:
                self.translate_channel_name[kwargs["sensor"]] = dataset.attrs[
                    "metadata_requirements"
                ]["translate"]
            except KeyError:
                # For some mitiff products this info is needed, for others not.
                # If needed you should know how to fix this
                pass

            image_description = self._make_image_description(dataset, **kwargs)
            gen_filename = filename or self.get_filename(**dataset.attrs)
            LOG.info("Saving mitiff to: %s ...", gen_filename)
            self._save_datasets_as_mitiff(
                dataset, image_description, gen_filename, **kwargs
            )
        except:
            raise

    create_opts = ()
    delayed = dask.delayed(_delayed_create)(create_opts, dataset)

    if compute:
        return delayed.compute()
    return delayed