Before going any further, understand that there are two ways of doing this. One requires you install Google Chrome. The other may not keep you current as quickly. Choose what you want to prioritize, then perform either of the steps below. Everything (at least when not using the Freshwrapper PPA) will be explained in-depth below. everything is broken now and you’re forced to do things a little differently.
#Why the update?
Google effectively broke the browser-plugin-freshplayer-pepperflash plugin with version 54 of Google Chrome, since they’ve seem to have discontinued Pepper Flash support there (as in, it’s not even in /opt/google!)
Since this has happened, I’m forced to revise this. To see the older version, simply view the previous edit of this thread.
#Cracking pepper
Using Ubuntu Artful?
If you still want to use this approach, and are using a legacy copy of Firefox (Firefox ESR, for instance) then you might encounter issues with this approach until you seek and install the 2.0 revisons of packages libevent-core and libevent-pthreads. Below are links for each:
https://packages.ubuntu.com/zesty/libevent-core-2.0-5
https://packages.ubuntu.com/zesty/libevent-pthreads-2.0-5
Core must be installed first, then pthreads as follows, if you cd to where you saved them:
sudo dpkg -i libevent-core-2.0-5* && sudo dpkg -i libevent-pthreads-2.0-5
After, the rest should continue without errors.
###Finding Pepper
Before reading on, I’ve uploaded the latest version of the shell object file required to MediaFire and made a redirect to it, which will be used below.
Begin with doing sudo apt install browser-plugin-freshplayer-pepperflash and letting that do its thing. When it comes to extracting the latest version of Chrome, this part of the install process will fail because Chrome 54 no longer has the PepperFlash directory. Now you can decide on what to do next with either series of events below;
###Giving Fresh Player what to expect
After performing the above, do the following;
sudo wget https://tinyurl.com/libpepflash -O /opt/google/chrome/PepperFlash/libpepflashplayer.so```
###Telling Fresh Player what to expect
If you'd rather define your own path for Pepper Flash, then the following will help you figure this out. I will assume the path for the shell object will be in `/opt` only, adjust to preference.
```wget https://raw.githubusercontent.com/i-rinat/freshplayerplugin/master/data/freshwrapper.conf.example -O ~/.config/freshwrapper.conf
sudo wget https://tinyurl.com/libpepflash -O /opt/libpepflashplayer.so```
After, open `~/.config/freshwrapper.conf` in your favourite text editor and scroll down; it seems line 40, the one that needs editing is commented out, but it still works; De-comment it and edit the path so it reads where you put it, in this case `/opt/libpepflashplayer.so`
#Why do this at all?
Because Flash is old and cranky on Linux. Previously Google Chrome had Peooer Flash support, though considering installing the latest version of Chrome doesn't provide the path to Pepper as expected (unless they changed it), I once again have to tell people to do it the hard way. It sucks, a lot and it's tedious but if you really need Flash because your favourite websites haven't updated to HTML5 content then this is one way which I know works. As for people who are concerned about sandboxing the browser (as Pepper Flash itself is sandboxed in Chrome), concerned users can perform the following;
`sudo apt-get install firejail`
Then run `firejail firefox` next time you want the browser, which firejail will then sandbox and execute. You can use firejail for other browsers and programs too, if you want to sandbox them as well.
#Information sources
http://www.webupd8.org/2016/03/fix-failed-to-fetch-google-chrome_3.html
http://www.webupd8.org/2014/05/install-fresh-player-plugin-in-ubuntu.html
The various people in this thread who made me curious enough to find out how to avoid installing Chrome.
#Corrections
Fixed the lacking sudo in the first series of commands (I assumed everybody realized my faux pas) and fixed the direct download link for MediaFire. Super-sorry about leaving this to rot prior. Also try out some of the other advice below if this guide doesn't work, but this is the most realiable way I can do things fo the time being.
Most recent update is to modify the reasoning behind performing the above. There is no reason I should be editing this further.
Open a Terminal 
and write these commands...
sudo apt-get update
sudo apt purge --remove adobe-flashplugin pepperflashplugin-nonfree flashplugin-installer
sudo apt-get install pepperflashplugin-nonfree
sudo apt-get install browser-plugin-freshplayer-pepperflash
If you installed adobe-flashplugin(step 4b) write this: sudo rm -f /usr/lib/adobe-flashplugin/libflashplayer.so
Close and open your browser again.
September/2017...From Colombia, South America 