I have problem when open a site that include flash player and the instruction is I should update my flash player. Usually I update it via adobe.com but some times it is not word and long loading. This is a solution.
Open Ubuntu Software and check suitable like the picture 1. Then type pepperflashplugin-nonfree on the search box and install it. The preview is show by picture 1 and picture 2 below.
If not work please open terminal and type this
sudo update-pepperflashplugin-nonfree –install
After it please restart our browser , good luck
reference : https://wiki.ubuntu.com/Chromium/Getting-Flash