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Initial thumbnail generation works but returns an error on first access
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First go at creating any thumbnail fails with …

Error generating thumbnail

Could not stream the file

… but then it's generated – not sure there's anything we can do to fix that?

Event Timeline

MarkTraceur changed the task status from Open to Stalled.Feb 10 2017, 8:51 PM

I suspect this is mostly a problem with the server timing out or being overloaded with the 40mb file that James tested with - we will test aggressively with big files on the beta cluster and see if this remains an issue.

dr0ptp4kt changed the task status from Stalled to Open.May 31 2017, 5:18 PM
dr0ptp4kt raised the priority of this task from Low to High.
dr0ptp4kt moved this task from Untriaged to Next up on the Multimedia board.
dr0ptp4kt added a subscriber: dr0ptp4kt.

We'll be revisiting this soon. This seems like a release blocker.

Some thoughts from our prioritization:

  • This is related to T166699 about performance, when I do that investigation I'll have a better idea of what's happening here
  • I've heard things about our ~40MB files being definitely problematic, so it will be good to see where the drop-off point is.
  • It might be good to rasterize the 3D model at a large bucket size right away (after upload), so we can downscale it instead of re-rendering every time we need a thumbnail.

I haven't been able to reproduce this on beta or on my machine, even with files up to ~150MB.
That said, a thumbnail does not appear for 3D uploads. It either says "Uploaded", without displayed a thumbnail, or "The upload succeeded, but the server could not get a preview thumbnail."

It seems that thumbnails failed to load because their mime type was unknown.
Since, the mime type for STL files is accurately being detected and thumbnail generation now also works in UW.
I've tested on my local machine with bin & plain stl files, from 11K to 40M+, and thumbnails seemed to generate just fine for all of them.

Hello, just checking on a few things. I believe that I have reproduced the issue on Beta.


  1. Went to
  2. Selected Upload File
  3. Used the Upload Wizard to add a file (about 644KB)
  4. On the upload page after adding the file the thumbnail is a simple icon (See pic 1)
  5. Eventually the broken thumbnail icon appears (see pic 2) and that icon continues to appear while finishing the upload

Pic 1

Pic 2

We believe we have a fix for the root cause, possibly some time this week. Heads up, @ABorbaWMF.

Working for me on Chrome, Safari, and Firefox now.