@daniel130461 , I use Linux Mint 19.1. VPN works fine.

@sgfdhsg , sometimes it is useful to clear browsing data. Navigate to opera://settings/clearBrowserData and check "Content settings" in Advanced tab. This helped me to make Flash working.

@zibi1981 , yes you are right! Chromium's libffmpeg.so is in /usr/lib/chromium-browser.

@sgfdhsg , maybe the problem is not in flash, but in libffmpeg.so? I had something like this two days ago.

@zalex108 , Flash works fine even without any special keys in Windows. But me discuss about Opera for Linux in this thread.

@l33t4opera , thank's for your detailed reply! I'll watch for Opera's behavior.

@l33t4opera , hi! It seems to me that the problem is in synchronization of Opera with my account. I remembered that I had something like this nearly a year ago. I changed my laptop. The previous synced data was made in 32 bit version of Opera, and the new one was in 64 bit. At that time there were similar problems with flash, as far as I remember. But I thought that they were gone since that time. I'll try to watch for this thing.
The interesting thing that this problem appeared in Chromium too. I don't have an account for that browser. And I use it very rarely.

I think the problem is solved. I cleared browsing data by selecting content check box. Now flash is working in Opera.

@jimunderscorep said in Flashplayer not working:

That last line came up when I ran the flash verification on adobe's page.

I see this line in Chromium. I removed and installed Chromium again. Flash works, but is not enabled there. I need to re-enable it on Adobe's page every time I start browser.
I can't understand, what block it to run in Opera. May be something wrong with my user profile?
P.S. I made a backup of my .config/opera dir, and then I start Opera. It created the new profile, and flash works fine there. How can I find, what's wrong in my profile?

@jimunderscorep , thank's for your reply. I tried to launch Opera with the key above. Nothing changed. Flash still not working.
I receive such output in terminal:

[1:8:0519/105120.031761:ERROR:command_buffer_proxy_impl.cc(105)] ContextResult::kTransientFailure: Shared memory region is not valid
[23838:23838:0519/105120.510525:ERROR:CONSOLE(0)] "Unchecked runtime.lastError while running operaTouchPrivate.getLocalName: Cannot obtain local name
    at chrome-extension://ebongfbmlegepmkkdjlnlmdcmckedlal/touch_communication.js:248:35", source: chrome-extension://ebongfbmlegepmkkdjlnlmdcmckedlal/page.html (0)
[23838:23838:0519/105121.247200:ERROR:CONSOLE(0)] "Uncaught (in promise) #<Object>", source: chrome-extension://obhaigpnhcioanniiaepcgkdilopflbb/background_worker.html (0)