Running Yosemite (10.10). Using Safari Version 8.0 (10600.1.25)
Not working here in any form. The offline installer quits at 40% and the online installer returns "process not elevated". I've uninstalled Flash and that had no result.


I see a few entries like this in the system logs:
10/20/14 01:43:46.492 Adobe Flash Player Install Manager[7233]: Persistent UI failed to open file file://localhost/~/Library/Saved%20Application%20State/com.adobe.flashplayer.installmanag er.savedState/window_1.data: Permission denied (13)
Here is the relevant part of the installer's log:
2014-10-20 01:57:12 -0400 [I] IM: ---------- log start ----------
2014-10-20 01:57:12 -0400 [I] IM: All install checks pass
2014-10-20 01:57:16 -0400 [E] IM: User has 1 process that needs to be closed before the Flash Player can be installed.
2014-10-20 01:57:22 -0400 [I] IM: [install started]
installer: Package name is Adobe Flash Player
installer: Installing at base path /
installer: The install failed (The Installer encountered an error that caused the installation to fail. Contact the software manufacturer for assistance.)
2014-10-20 01:57:32 -0400 [I] IM: [install completed]
2014-10-20 01:57:32 -0400 [E] IM: [install failed]
2014-10-20 01:58:44 -0400 [I] IM: ---------- log end ----------
2014-10-20 02:20:35 -0400 [I] IM: ---------- log start ----------
2014-10-20 02:20:38 -0400 [I] IM: 1407
2014-10-20 02:20:43 -0400 [I] IM: ---------- log start ----------
2014-10-20 02:20:44 -0400 [I] IM: 1407
2014-10-20 02:20:45 -0400 [I] IM: 1407
2014-10-20 02:20:49 -0400 [I] IM: ---------- log end ----------
It looks like the installer is trying to access that folder as if it were a Windows folder, instead of using shell escapes to include the spaces. A guess.
Also, the com.adobe.flashplayer.installmanager.savedState is only readable by "system" and no-one else. I cannot access it even as administrator.
Hope this helps.