Webplayer not working in FF39

Hi all!

Not sure how to go about this, but I think I encountered a bug. I would like a second opinion before filing it as a bug, though.

Currently we are working on a new portal, which includes one game. While I was working yesterday, doing some tests, I had to restart the browser (Firefox Developer Edition) and upgraded to version 39.0a2 (2015-04-09). From that moment on, the Unity webplayer (version 5.0.1.11919 / 5.0.1f1) was no longer able to load the game data file ("Failed to download data file"). As far as I can tell the webplayer is working properly when loading from the local filesystem, but not when loaded from a local test server. Using the exact same address in Firefox version 37 is working as expected.

Looking at the traffic I noticed that the status of the file was "206 Partial Content". Attached you will find screenshots of the headers of both the working version in FF37 and the failing version in FF39. You will see that the request headers differ and that the request from FF39 is asking for byte serving. Since the exact same code is being used in both browsers (all caches were emptied and we re-tested before posting this thread) I cannot think of any reason why this occurs, except for maybe the UnityObject2.js file is doing something wrong. No clue what that could be, though... Otherwise it might be jQuery (latest version), but I don't think so.

What are your thoughts? Is it a bug, or am I just missing something? Any feedback would be greatly appreciated!

Working in FF37:


Not working in FF39:

 

Update: as of now, after an update of Firefox Developer Edition this morning, everything seems to be working as expected. So I am guessing it was a FF bug. Glad to see we can still use the Webplayer in Firefox in the near future.