ValueError: Empty key names are not allowed when using collectstatic django

I am using django-pipeline S3PipelineManifestStorage with django-storages

When I use collectstatic to upload and post-process(minify) my assets, I get an error when post-processing.

Earlier, collectstatic worked fine and gave no error.

Here's the full traceback

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/app/.heroku/python/lib/python2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
    utility.execute()
  File "/app/.heroku/python/lib/python2.7/site-packages/django/core/management/__init__.py", line 330, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/app/.heroku/python/lib/python2.7/site-packages/django/core/management/base.py", line 390, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/app/.heroku/python/lib/python2.7/site-packages/django/core/management/base.py", line 441, in execute
    output = self.handle(*args, **options)
  File "/app/.heroku/python/lib/python2.7/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py", line 168, in handle
    collected = self.collect()
  File "/app/.heroku/python/lib/python2.7/site-packages/django/contrib/staticfiles/management/commands/collectstatic.py", line 114, in collect
    for original_path, processed_path, processed in processor:
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/storage.py", line 26, in post_process
    packager.pack_stylesheets(package)
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/packager.py", line 96, in pack_stylesheets
    variant=package.variant, **kwargs)
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/packager.py", line 105, in pack
    paths = self.compile(package.paths, force=True)
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/packager.py", line 34, in paths
    return [path for path in self.sources
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/packager.py", line 26, in sources
    for path in glob(pattern):
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/glob.py", line 18, in glob
    return sorted(list(iglob(pathname)))
  File "/app/.heroku/python/lib/python2.7/site-packages/pipeline/glob.py", line 29, in iglob
    if staticfiles_storage.exists(pathname):
  File "/app/.heroku/python/lib/python2.7/site-packages/storages/backends/s3boto.py", line 445, in exists
    k = self.bucket.new_key(self._encode_name(name))
  File "/app/.heroku/python/lib/python2.7/site-packages/boto/s3/bucket.py", line 623, in new_key
    raise ValueError('Empty key names are not allowed')
ValueError: Empty key names are not allowed

Could you please figure out why this error is occuring?

It was an issue with Pipeline settings PIPELINE_CSS ={ 'maths_landing_page':{ 'source_filenames':( 'html/css/maths-landing-page.css' ), 'output_filename':'html/css/maths-landing-page-consolidated.css', } }

While the actual settings was PIPELINE_CSS ={ 'maths_landing_page':{ 'source_filenames':( 'html/css/maths-landing-page.css', ), 'output_filename':'html/css/maths-landing-page-consolidated.css', } }

Notice the comma in the tuple.

Apparently.

>>> type( ('a') )
<type 'str'>

>>> type( ('a',) )
<type 'tuple'>