I don't know if this is something you can actually mitigate, since it seems to stem from an OS file locking problem, but if you try and upload a CSV file that's still open in Excel, for example, then the import process fires off, but just spins for ages before timing out with a fatal-looking 'Service Unavailable' message.
The message actually looks similar to IIS error messages (deliberate?) which gives the impression that the service is down at your end, but in fact the moment you shut the local file down and retry the import, it works instantly.
I'm running Mac OS X 10.6.8 and Safari 5.1 although I suspect this holds true for any version of OS X. I haven't had chance to test this under Windows yet.
I appreciate the logical answer will be "don't try and upload open files" but that situation is actually easier to get into without realising than you might think. If I have an XLS file open in Excel and do a "Save as..." to export to CSV format, rather than writing that file separately and keeping the original XLS file open, Excel switches the open file to the CSV you just exported. Unless you have an eagle eye on the document title bar, the change is not immediately obvious, and the problem of working on open files wouldn't necessarily occur to you.
To me it seems that Safari is likely at fault for not reporting that the file cannot be worked on, but as I say, the message you then get from Campaign Monitor makes it look as though the service itself is at fault, rather than being unable to grab the data via the browser.
Hi Ian, thank you so much for providing these details! Admittedly I haven't come across this one before and totally agree that the 'Service Unavailable' message is a totally scary response to a rather benign issue.
What I'll do at this point is bug it up and get our team across this. It most certainly seems like an error we should be catching, so we'll look at how we can handle this better in the future.
Thanks again for providing all these details - it's a huge help. Btw, we're at .NET shop here, so generally when there are errors that the app doesn't know how to deal with, you get that hella ugly IIS error page :P Sorry again for this!
This one got me too. Not an ideal experience, and at odds with the rest of CM.
+1 for a fix.
Sorry about this, graphicsSA - I've just given this issue a nudge internally, so hopefully our devs will look in a way to handle this error more gracefully in the future. Sorry again for the bad look here, I agree it's really not a very helpful (or nice) screen to show!