I get an error message when uploading an .mp3: "If you're sure your internet connection works, then we recommend you either use Google Chrome (this is the recommended option - you don't actually need Flash if you're using Chrome), or install Flash." This statement confuses me since I am using Chrome, my connection is good, and I do have Flash installed.
Hmmm. Thanks for reporting. Mixlr uses WebSockets when available (i.e., Chrome) and falls back to Flash, so this error probably means the WebSocket port was blocked for some reason, maybe a firewall. I agree the error message is a bit skewed in this case. I am going to do some more work to minimize this kind of problem, it's not perfect yet.