I hit a problem last night where projects built using beta2 wouldn't output correctly from beta3. On running the HTML file from output, the browser screen just displays the message
I tried various outputs, file paths and names but to no avail; also tested it with Flash turned on and off in serval browsers, and using the integrated server. All to no avail. Ended up reverting back to beta2 (glad I saved all previous installers on my computer,so could do this) and the project outputted and worked perfectly once more…This content requires HTML5/CSS3, WebGL, or Adobe Flash Player Version 9 or higher.
Admittedly it wasn't a 'vanilla' project - it's dual HTML5 & Flash with quite a bit of interactivity, and uses custom Javascript triggers in the HTML template. However it's an odd occurrence and I'd advise double-checking in case you experience something else with a live, legacy job…
Can supply files privately to the developers if they'd like to try and reproduce this issue… thanks