IIS 412 error

Nov 27, 2008 at 9:16 PM

We have a user who uploaded a series of files totally 20.2 MB (9 files) to the server.  The user received an email and clicked one of the files and the velodoc xp page presented the user with an error message "precondition not found"

We then sent the download urls to several employees to see if they could access the files - many users were able to successfully download the files and 2 other employees received the precondition not found error.

We traced down the 412 error 

The IIS logs do not tell us anything other than the time when the problem occurred.

Any ideas / suggestions?

Nov 28, 2008 at 12:23 PM
Edited Dec 1, 2008 at 8:56 AM
This error is reported by the DownloadHandler in Velodoc XP Edition, which provides resumable downloads, in particular when it gets unexpected values in the Http header fields "If-Modified-Since" and/or "If-Unmodified-Since". I have experienced this error a couple of times but it is very difficult to reproduce because it depends on the status of the browser cache.

The workaround which has always worked for me is to refresh the page or click the download link while pressing Ctrl + Shift to ensure that you bypass the browser cache (Note that you should normally use the Ctrl key in IE and the Shift key in Firefox, but the combination of both always works).