Personal Message:
I am an office operator.
I have been using Android Opera and Firefox for many years, but I have been noticing small bug in Opera browser for many years and have been informing your team continue.
But you all do not care my words.
Opera Error:
When I want to view online embed PDF file on web page it shows "PDF Plugin Couldn't Supported" . It only gives the option to download, which is not what I want.
On the other hand, when I open Android Firefox in Mozilla, it opens the PDF file and shows it. There is no error there.