I am seeing this all over the forums with no one finding a solution. I have tried everything suggested either in Safari or Firefox including a clean install 3 times!! Even after uninstalling and deleting the flash files in the library, when I go to try downloading and installing it immediately starts at 30% and then I get the error message "Lost connection. Trying to connect...." then it hangs for a bit and then I get "Connection failed. Unable to complete installation." I go to their support link when the install fails but the link that they suggest to download from directly in the final step is "NOT FOUND". See here: Installation problems | Flash Player | Mac
This same link is showing up in several forums for a solution. I don't know what else to do. I'm posting this to add to the many many others with the same issue in hopes that Adobe will fix this! I am on a MAC OS 10.9.5. Never had this issue before with the flash updates!!!
I am having the exact same problem, except running on Mac. Would really like to find out the solution. Please please please pass on any information if you figure it out.
Solution found on another thread. Download the offline installer here: http://fpdownload.macromedia.com/pub/flashplayer/current/support/install_flash_player_osx. dmg
I downloaded and was able to install Flash properly. Make sure you do a clean install just to be sure.
Thank you very much for your help! It is working now! I tried the offline installer, but didn't work, this link worked perfectly.