I have a MacBook running El Capitan 10.11.6 (15G31) and I am not able to install Flash Player. I have downloaded the file : AdobeFlashPlayer_22_a_install-7.dmg. (it reads 7 because I have downloaded the file numerous times. the same thing happens when I try to open the original version). When I click on it, a window opens: and then it freezes. Nothing happens when I click on the install button. I have followed the trouble-shooting steps. I have had this problem for a long time, even before the current version of El Capitan. Apple customer service can't help. Flash player used to update automatically. Then it stopped and I have had this problem ever since. I have tried uninstalling Flash Player and rebooting to try to get a fresh start. No luck. Any advice?
Do you experience this behaviour with any other DMG file? Double-clicking the DMG file simply mounts the DMG file enabling you to manipulate the files inside.
Have you tried booting into safe mode and attempting to install it in safe mode?
See Try safe mode if your Mac doesn't finish starting up - Apple Support for information on starting your computer in safe mode.
This was helpful. After many hours of working on this, installing in "safe mode" was the key. I printed the post "How to perform a "clean install" of Flash Player in Mac OS X and followed the directions exactly, BUT ADDING two steps: 1) before rebooting, Log Out of your screen - this is where you can unselect the option to "reopen windows when logging back in" and 2)hold the Shift key down while rebooting to make it reboot in Safe Mode.
Now my son will be able to do his online math homework!
I hope this helps someone else someday.