IO.FileNotFound_FileName exception when selecting a file in Silverlight

I don’t know how much this will help people – there’s only 7 results on Google for “IO.FileNotFound_FileName” at the time of writing so it’s clearly not a common problem – but one of our Mac users just reported an issue with selecting a file via a custom Silverlight control. They do this process day in, day out, but suddenly started getting the following error message:

Silverlight IO.FileNotFound_FileName exception

Silverlight IO.FileNotFound_FileName exception

I couldn’t find any evidence of people getting this problem before, the MS page it pointed me to was typically useless. The only suggestion I came across was that it might relate to diskspace having run out, but neither the Mac nor the external fileserver this file was being loaded from were low on space so that ruled that one out.

From a process of trial and error I managed to track the problem down to the folder these files were stored in which, whilst it appeared perfectly normal when viewed on a Mac, when accessed via Windows showed up as gobbledygook. Creating a new folder and copying all the contents over did the trick – the file could be selected and uploaded as before.

Clearly something went very screwy deep down in the OSX filesystem with that folder, though I have absolutely no idea what it might have been. Maybe I missed something really obvious (I have no experience with Macs to call on), but hopefully by bumping the number of Google results up to 8 I might one day save somebody a bit of time 🙂

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