When an SVG file is uploaded, mediagoblin.media_types.video accepts the file and tries to transcode and create a thumbnail of the file. Debug output follows. Attached is a screenshot of how an SVG appears after being processed by mediagoblin.media_types.video. In this instance, the SVG plugin is not installed. This issue may not apply if the SVG plugin is installed.

09:51:53,585 INFO    [mediagoblin.media_types] No media handler found by file extension. Doing it the expensive way...
09:51:53,588 INFO    [mediagoblin.media_types.image.processing] Sniffing mediagoblin.media_types.image
09:51:53,589 DEBUG   [mediagoblin.media_types.image.processing] Media present, extension not found in ['png', 'gif', 'jpg', 'jpeg', 'tiff']
09:51:53,589 INFO    [mediagoblin.media_types.audio.processing] Sniffing mediagoblin.media_types.audio
09:51:53,589 INFO    [mediagoblin.media_types.audio.transcoders] Initializing AudioTranscoder
09:51:53,589 INFO    [mediagoblin.media_types.audio.transcoders] Discovering /tmp/tmp48IrtU
09:51:53,623 DEBUG   [mediagoblin.media_types.audio.transcoders] Discovered: {'_timeoutid': 0, 'audiocaps': {}, 'audiodepth': 0, 'videowidth': 554, 'audiofloat': False, 'dbin': <__main__.GstDecodeBin object (decodeb
in0) at 0x7f19041d1410>, '_nomorepads': True, 'audiorate': 0, 'audiochannels': 0, 'audiowidth': 0, 'videoheight': 102, 'tags': {}, 'bus': <gst.Bus object (bus1) at 0x7f19041d1690>, 'finished': True, 'typefind': <__main__.GstTy
peFindElement object (typefind) at 0x7f19041d1500>, 'videorate': <gst.Fraction 0/1>, 'src': <__main__.GstFileSrc object (filesrc0) at 0x7f19041d14b0>, 'mimetype': 'image/svg+xml', 'audiolength': 0L, 'videolength': -1, 'otherst
reams': [], 'sinknumber': 1, '_max_interleave': 1.0, '_success': True, 'videocaps': <GstCaps at 0x7f18c400a140>, '_timeout': 3000, 'is_audio': False, 'is_video': True}
09:51:53,623 INFO    [mediagoblin.media_types.audio.transcoders] Quitting MainLoop gracefully...
09:51:53,623 INFO    [mediagoblin.media_types.video.transcoders] Initializing VideoTranscoder...
09:51:53,623 INFO    [mediagoblin.media_types.video.transcoders] Discovering /tmp/tmp48IrtU
09:51:53,623 DEBUG   [mediagoblin.media_types.video.transcoders] Setting up discoverer
09:51:53,633 DEBUG   [mediagoblin.media_types.video.transcoders] Discovered: /gst+extend+discoverer+Discoverer:gst+extend+discoverer+discoverer1 (Discoverer)
09:51:53,633 INFO    [mediagoblin.media_types.video.transcoders] Terminating MainLoop
09:51:53,634 INFO    [mediagoblin.media_types.video.processing] Sniffing mediagoblin.media_types.video
09:51:53,634 DEBUG   [mediagoblin.media_types.video.processing] Discovered: {'_timeoutid': 0, 'audiocaps': {}, 'audiodepth': 0, 'videowidth': 554, 'audiofloat': False, 'dbin': <__main__.GstDecodeBin object (decodebin1) at 0x7f19041d1140>, '_nomorepads': True, 'audiorate': 0, 'audiochannels': 0, 'audiowidth': 0, 'videoheight': 102, 'tags': {}, 'bus': <gst.Bus object (bus4) at 0x7f19041d1730>, 'finished': True, 'typefind': <__main__.GstTypeFindElement object (typefind) at 0x7f19041d10f0>, 'videorate': <gst.Fraction 0/1>, 'src': <__main__.GstFileSrc object (filesrc1) at 0x7f19041d10a0>, 'mimetype': 'image/svg+xml', 'audiolength': 0L, 'videolength': -1, 'otherstreams': [], 'sinknumber': 1, '_max_interleave': 1.0, '_success': True, 'videocaps': <GstCaps at 0x7f18c400a2c0>, '_timeout': 3000, 'is_audio': False, 'is_video': True}
09:51:53,634 INFO    [mediagoblin.media_types] mediagoblin.media_types.video accepts the file
09:51:53,676 DEBUG   [mediagoblin.processing.task] Processing <MediaEntry 30: MediaGoblin_logo>
09:51:53,676 INFO    [mediagoblin.media_types.video.transcoders] Initializing VideoTranscoder...
09:51:53,679 INFO    [mediagoblin.media_types.video.transcoders] Discovering /path/to/mediagoblin/user_dev/media/queue/media_entries/hash/MediaGoblin_logo.svg
09:51:53,679 DEBUG   [mediagoblin.media_types.video.transcoders] Setting up discoverer
09:51:53,686 DEBUG   [mediagoblin.media_types.video.transcoders] Discovered: /gst+extend+discoverer+Discoverer:gst+extend+discoverer+discoverer2 (Discoverer)
09:51:53,686 INFO    [mediagoblin.media_types.video.transcoders] Terminating MainLoop
09:51:53,688 DEBUG   [mediagoblin.media_types.video.util] skip_transcode config: {u'mime_types': [u'video/webm'], u'container_formats': [u'Matroska'], u'video_codecs': [u'VP8 video'], u'audio_codecs': [u'Vorbis'], u'dimensions_match': True}
09:51:53,688 DEBUG   [mediagoblin.media_types.video.transcoders] Setting up discoverer
09:51:53,690 DEBUG   [mediagoblin.media_types.video.transcoders] Setting up transcoding pipeline
09:51:53,707 INFO    [mediagoblin.media_types.video.transcoders] Discovering...
09:51:53,709 INFO    [mediagoblin.media_types.video.transcoders] Done
09:51:53,709 DEBUG   [mediagoblin.media_types.video.transcoders] Initializing MainLoop()
09:51:53,712 DEBUG   [mediagoblin.media_types.video.transcoders] __discovered, data: {'_timeoutid': 0, 'audiocaps': {}, 'audiodepth': 0, 'videowidth': 554, 'audiofloat': False, 'dbin': <__main__.GstDecodeBin object (decodebin3) at 0x7f1904585820>, '_nomorepads': True, 'audiorate': 0, 'audiochannels': 0, 'audiowidth': 0, 'videoheight': 102, 'tags': {}, 'bus': <gst.Bus object (bus10) at 0x7f19088945f0>, 'finished': True, 'typefind': <__main__.GstTypeFindElement object (typefind) at 0x7f1904585aa0>, 'videorate': <gst.Fraction 0/1>, 'src': <__main__.GstFileSrc object (filesrc3) at 0x7f1904585730>, 'mimetype': 'image/svg+xml', 'audiolength': 0L, 'videolength': -1, 'otherstreams': [], 'sinknumber': 1, '_max_interleave': 1.0, '_success': True, 'videocaps': <GstCaps at 0x7f18c400a600>, '_timeout': 3000, 'is_audio': False, 'is_video': True}
09:51:53,712 DEBUG   [mediagoblin.media_types.video.transcoders] linking elements
09:51:53,727 INFO    [mediagoblin.media_types.video.transcoders] Transcoding...
...
09:51:53,779 INFO    [mediagoblin.media_types.video.transcoders] 100% done...
09:51:53,780 DEBUG   [mediagoblin.media_types.video.transcoders] {'current': 9520, 'total': 9520, 'percent': 100, 'percent-double': 100.0, 'format': <enum GST_FORMAT_BYTES of type GstFormat>}
09:51:53,780 DEBUG   [mediagoblin.media_types.video.transcoders] (<gst.Bus object (bus13) at 0x7f1908894460>, <gst.Message (none) from VideoTranscoderPipeline at 0x7f18cc0048b0>, <flags GST_MESSAGE_EOS of type GstMessageType>)
09:51:53,782 INFO    [mediagoblin.media_types.video.transcoders] Done
09:51:53,784 DEBUG   [mediagoblin.media_types.video.transcoders] <glib.MainLoop object at 0x7f19044cc870>
09:51:53,785 INFO    [mediagoblin.media_types.video.transcoders] Terminating MainLoop
09:51:53,789 DEBUG   [mediagoblin.media_types.video.processing] Saving medium...
09:51:53,791 DEBUG   [mediagoblin.media_types.video.processing] Saved medium
09:51:53,828 DEBUG   [mediagoblin.media_types.video.transcoders] playbin state changed:
prev: <enum GST_STATE_NULL of type GstState>
cur: <enum GST_STATE_READY of type GstState>
 pending: <enum GST_STATE_PAUSED of type GstState>
...
09:51:53,833 INFO    [mediagoblin.media_types.video.transcoders] playbin ready
09:51:53,833 CRITICA [mediagoblin.media_types.video.transcoders] Could not get any video data from playbin
09:51:53,833 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 1: query failed
09:51:53,833 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 2: query failed
09:51:53,833 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 3: query failed
09:51:53,834 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 4: query failed
09:51:53,834 CRITICA [mediagoblin.media_types.video.transcoders] Pipeline duration query retry limit reached.
09:51:53,834 DEBUG   [mediagoblin.media_types.video.transcoders] thumbnail_pipeline: filesrc location="/path/to/mediagoblin/user_dev/media/queue/media_entries/hash/MediaGoblin_logo.svg" ! decodebin2 ! ffmpegcolorspace ! videoscale ! video/x-raw-rgb,depth=24,bpp=24,pixel-aspect-ratio=1/1,width=180 ! fakesink signal-handoffs=True
09:51:53,859 DEBUG   [mediagoblin.media_types.video.transcoders] thumbnail state changed:
prev: <enum GST_STATE_NULL of type GstState>
cur: <enum GST_STATE_READY of type GstState>
 pending: <enum GST_STATE_VOID_PENDING of type GstState>
...
09:51:53,860 INFO    [mediagoblin.media_types.video.transcoders] Could not seek.
...
09:51:53,867 ERROR   [mediagoblin.media_types.video.transcoders] thumbnail error: [<GError at 0x7f18f83e5570>, 'gstvideoscale.c(779): gst_video_scale_fixate_caps (): /GstPipeline:pipeline0/GstVideoScale:videoscale0:\nError calculating the output scaled size - integer overflow']
09:51:53,867 ERROR   [mediagoblin.media_types.video.transcoders] thumbnail error: [<GError at 0x7f18f83e56c0>, 'gstvideoscale.c(779): gst_video_scale_fixate_caps (): /GstPipeline:pipeline0/GstVideoScale:videoscale0:\nError calculating the output scaled size - integer overflow']
09:51:53,867 DEBUG   [mediagoblin.media_types.video.transcoders] thumbnail state changed:
prev: <enum GST_STATE_READY of type GstState>
cur: <enum GST_STATE_PAUSED of type GstState>
 pending: <enum GST_STATE_VOID_PENDING of type GstState>
09:51:53,867 INFO    [mediagoblin.media_types.video.transcoders] Could not seek.
09:51:53,867 ERROR   [mediagoblin.media_types.video.transcoders] Thumbnailing failed because of videoscale integer overflow. Will retry with fallback.
09:51:53,876 INFO    [mediagoblin.media_types.video.transcoders] Retrying with manually set sizes...
09:51:53,876 INFO    [mediagoblin.media_types.video.transcoders] Initializing VideoTranscoder...
09:51:53,876 INFO    [mediagoblin.media_types.video.transcoders] Discovering /path/to/mediagoblin/user_dev/media/queue/media_entries/hash/MediaGoblin_logo.svg
09:51:53,876 DEBUG   [mediagoblin.media_types.video.transcoders] Setting up discoverer
09:51:53,879 ERROR   [mediagoblin.media_types.video.transcoders] Thumbnailing failed because of videoscale integer overflow. Will retry with fallback.
09:51:53,879 INFO    [mediagoblin.media_types.video.transcoders] Retrying with manually set sizes...
09:51:53,879 INFO    [mediagoblin.media_types.video.transcoders] Initializing VideoTranscoder...
09:51:53,879 INFO    [mediagoblin.media_types.video.transcoders] Discovering /path/to/mediagoblin/user_dev/media/queue/media_entries/hash/MediaGoblin_logo.svg
09:51:53,879 DEBUG   [mediagoblin.media_types.video.transcoders] Setting up discoverer
09:51:53,882 DEBUG   [mediagoblin.media_types.video.transcoders] Discovered: /gst+extend+discoverer+Discoverer:gst+extend+discoverer+discoverer5 (Discoverer)
09:51:53,882 INFO    [mediagoblin.media_types.video.transcoders] Terminating MainLoop
09:51:53,883 DEBUG   [mediagoblin.media_types.video.transcoders] Discovered: /gst+extend+discoverer+Discoverer:gst+extend+discoverer+discoverer6 (Discoverer)
09:51:53,883 INFO    [mediagoblin.media_types.video.transcoders] Terminating MainLoop
09:51:53,904 DEBUG   [mediagoblin.media_types.video.transcoders] playbin state changed:
prev: <enum GST_STATE_NULL of type GstState>
cur: <enum GST_STATE_READY of type GstState>
 pending: <enum GST_STATE_PAUSED of type GstState>
...
09:51:53,909 INFO    [mediagoblin.media_types.video.transcoders] playbin ready
09:51:53,909 CRITICA [mediagoblin.media_types.video.transcoders] Could not get any video data from playbin
09:51:53,909 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 1: query failed
09:51:53,909 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 2: query failed
09:51:53,909 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 3: query failed
09:51:53,910 ERROR   [mediagoblin.media_types.video.transcoders] Could not get duration on attempt 4: query failed
09:51:53,910 CRITICA [mediagoblin.media_types.video.transcoders] Pipeline duration query retry limit reached.
09:51:53,910 DEBUG   [mediagoblin.media_types.video.transcoders] thumbnail_pipeline: filesrc location="/path/to/mediagoblin/user_dev/media/queue/media_entries/hash/MediaGoblin_logo.svg" ! decodebin2 ! ffmpegcolorspace ! videoscale ! video/x-raw-rgb,depth=24,bpp=24,pixel-aspect-ratio=1/1,width=180,height=33 ! fakesink signal-handoffs=True
09:51:53,936 DEBUG   [mediagoblin.media_types.video.transcoders] thumbnail state changed:
prev: <enum GST_STATE_NULL of type GstState>
cur: <enum GST_STATE_READY of type GstState>
 pending: <enum GST_STATE_VOID_PENDING of type GstState>
...
09:51:53,937 INFO    [mediagoblin.media_types.video.transcoders] Could not seek.
...
09:51:56,863 CRITICA [mediagoblin.media_types.video.transcoders] Reached gobject timeout
09:51:56,930 DEBUG   [mediagoblin.media_types.video.transcoders] playbin state changed:
prev: <enum GST_STATE_NULL of type GstState>
cur: <enum GST_STATE_READY of type GstState>
 pending: <enum GST_STATE_PAUSED of type GstState>
...
09:51:56,936 CRITICA [mediagoblin.media_types.video.transcoders] Reached gobject timeout
09:51:56,970 DEBUG   [mediagoblin.tools.processing] No processing callback for <MediaEntry 30: MediaGoblin_logo>

When a user registers, the chosen username is lowercased before being stored to the database. When a user attempts to log in, the supplied username is passed through as it was typed, which may contain uppercase letters. A user who registered his or her name using uppercase letters may not realize that the username was lowercased internally and may continue trying to log in with uppercase letters.

After a failed login attempt with uppercase letters, the login form helpfully displays the username lowercased. However, it still may not be clear to the end user that he or she needs to log in with that lowercased username.

Following another user's Blog Dashboard link shows a list of that user's blogs. Clicking on one of the listed blogs produces unexpected results.

1. If USER1 is logged in and clicks on one of USER2's blogs from USER2's Blog Dashboard, USER1 sees a 404 page.
2. If a user who is not logged in clicks on one of any USER's blogs from USER's Blog Dashboard, the unauthenticated user sees SERVER ERROR.

This is caused by the below snippet of code.

mediagoblin/media_types/blog/views.py:

def blog_post_listing(request, page, url_user=None):
    """
    Page, listing all the blog posts of a particular blog.
    """
    blog_slug = request.matchdict.get('blog_slug', None)
    blog = get_blog_by_slug(request, blog_slug, author=request.user.id)
    if not blog:
        return render_404(request)

In case 1 above, request.user.id will become the id of USER1, so blog returns empty (unless, I assume, USER1 has an identical blog slug to USER2).

In case 2 above, request.user.id produces a server error with the following text:

Error - <type 'exceptions.AttributeError'>: 'NoneType' object has no attribute 'id'
URL: https://domain.tld/mediagoblin/u/USER/b/BLOG/
File '/path/to/mediagoblin/lib/python2.7/site-packages/Paste-1.7.5.1-py2.7.egg/paste/exceptions/errormiddleware.py', line 144 in __call__
  app_iter = self.application(environ, sr_checker)
File '/path/to/mediagoblin/lib/python2.7/site-packages/Paste-1.7.5.1-py2.7.egg/paste/urlmap.py', line 203 in __call__
  return app(environ, start_response)
File '/path/to/mediagoblin/mediagoblin/app.py', line 265 in __call__
  return self.call_backend(environ, start_response)
File '/path/to/mediagoblin/mediagoblin/app.py', line 242 in call_backend
  response = controller(request)
File '/path/to/mediagoblin/mediagoblin/decorators.py', line 114 in wrapper
  return controller(request, *args, url_user=user, **kwargs)
File '/path/to/mediagoblin/mediagoblin/decorators.py', line 165 in wrapper
  return controller(request, page=page, *args, **kwargs)
File '/path/to/mediagoblin/mediagoblin/media_types/blog/views.py', line 264 in blog_post_listing
  blog = get_blog_by_slug(request, blog_slug, author=request.user.id)
AttributeError: 'NoneType' object has no attribute 'id'