bug report: 2.0 alpha - file corruption using Flash uploader when user "starts-stops-restarts" #702

filmo opened this Issue Jan 29, 2013 · 1 comment


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filmo commented Jan 29, 2013


  • html5 runtime unavailable, falls over to Flash runtime
  • user is uploading file large enough that it needs to be 'chunked'
    Example: 16 MB file
  • user starts upload in UI widget via "Start Upload" button
  • user then clicks 'stop' upload while file is in process of uploading.
    Example: "File A.mp4" is 17% uploaded when user 'stops upload'
  • user 'restarts' the upload using the 'start' button again.

Corrupted File Upload. Sporadically either less data than file uploaded (parts of chunks are lost) or more data in upload file than original (parts of chunks are uploaded multiple times)

using openssl md5 I can confirm that the local file does not match what ends up on the server.

Additional information:
works as expected when just allowing the upload to progress as normal. (no "start-stop-restarting")

Possible work arounds:
If runtime == 'flash' and upload is stopped while in progress, then that particular file's "completed amount" is reset to 0 such that when 'start' is pressed again, the entire file is reuploaded starting from 0.

If runtime == 'flash' and user clicks 'stop upload', warning screen pops up FIRST asking for confirmation and informing user that entire file will need to be re-uploaded if he or she decides to 'restart' the upload again. This can be big issue if the user has already spent 2 hours uploading the first 550 MB of a 600 MB file !!

Other options ???

Tested environments where error occurred:
IE9 on Windows 7
Safari 5.x on Mac 10.6.x
(did not test any other flash-only environments. error may occur on them as well.)

runtimes : 'html5,flash,silverlight',
required_features: 'access_binary', 
Results on Server after "Start-Stop-Restart":
user@srv04 [/home/product/public_html/clientarea/ftp/RP/4916]# openssl md5 *
MD5(test_only.aif)= 2e4f38f1f9cebcc9231b250a5576b957

Results from Server File for just a straight upload:
user@srv04 [/home/product/public_html/clientarea/ftp/RP/4916]# openssl md5 *
MD5(test_only.aif)= e01677f93a0b04e220ef159804448dc1

Original MD5 of file = e01677f93a0b04e220ef159804448dc1
jayarjo commented Feb 5, 2013

Yes I can confirm that, I'm working on alternative chunking solution, that doesn't simply append data to the end of the file (which will obviously fail if there was already an upload that was canceled), but will write a chunk at a specified offset in the temp file.

@jayarjo jayarjo added a commit that referenced this issue Feb 16, 2013
@jayarjo jayarjo Send offset/total instead of chunk/chunk - more informative and also …
…will give us opportunity to retry particular chunks for whatever reason. Address #702. Update moxiecode/moxie@8709035.
@jayarjo jayarjo closed this Feb 16, 2013
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