I've tried all the recommended uninstall, trash, reboot etc and still get the same thing. Now of course since I went through all that I don't even have the previous version. If Adobe is going to nag me every 5 minutes to do an installation the least they could do is make sure it works! This is really annoying.
The console shows, after the download completes
12/30/14 11:36:29.000 AM kernel: hfs: summary table not allowed on FS with block size of 2048
12/30/14 11:36:29.000 AM kernel: hfs: could not initialize summary table for Flash Player
12/30/14 11:36:29.000 AM kernel: hfs: mounted Flash Player on device disk3s2
12/30/14 11:36:29.473 AM mds: (Volume.Normal:2464) volume:0x7ffb5c86b000 ********** Bootstrapped Creating a default store:1 SpotLoc:(null) SpotVerLoc:(null) occlude:0 /Volumes/07015b73d58a8ccf952da8487462030adc1ba916
12/30/14 11:36:30.757 AM SIMBL Agent: warning: failed to get scripting definition from /Volumes/07015b73d58a8ccf952da8487462030adc1ba916/Install Adobe Flash Player.app; it may not be scriptable.
12/30/14 11:36:30.757 AM SIMBL Agent: AppleEvents: Send port for process has no send right, port=( port:27751/0x6c67 rcv:1,send:0,d:0 limit:5) (findOrCreate()/AEMachUtils.cp #526) com.apple.main-thread
12/30/14 11:36:30.758 AM SIMBL Agent: AppleEvents: Send port for process has no send right, port=( port:27751/0x6c67 rcv:1,send:0,d:0 limit:5) (findOrCreate()/AEMachUtils.cp #526) com.apple.main-thread
12/30/14 11:36:30.788 AM authexec: executing /bin/sleep
12/30/14 11:36:30.817 AM authexec: executing /usr/sbin/chown
12/30/14 11:36:30.932 AM authexec: executing /bin/chmod
12/30/14 11:36:31.046 AM authexec: executing /bin/chmod
12/30/14 11:36:31.163 AM authexec: executing /bin/chmod
12/30/14 11:36:31.275 AM authexec: executing /bin/rm
12/30/14 11:36:31.000 AM kernel: hfs: unmount initiated on Flash Player on device disk3s2
I updated to MacOS 10.10.1, no change. If only their F-ing install process would TELL YOU what went wrong. "failed to install" is SOOOO helpful.
This finally worked. I have no idea why. I'd been running for half a day or so without it installed since uninstalling. I ran the uninstaller yet again, rebooted, then ran the installer with the filename of install_flash_player_osx.dmg not the one where a hex revision of some sort is included in the filename. This completed and installed 16.0 .