To start, Please follow the Uninstall instructions posted here: Uninstall Flash Player | Mac OS
Download the offline installer posted at the bottom of the Installation problems | Flash Player | Mac page, in the 'Still need help' section.
- There are two types Flash Player plugins: NPAPI for Firefox/Safari browsers, and PPAPI for Opera and Chromium-based browsers. Download the one(s) for the browser(s) you are using.
If it won't download directly, right click and "Save as"… and make note of the save location
DO NOT mount the installer DMG or run the installer yet!
Empty the trash
Quit your Browser (Press Cmd+Q - Don't just close the window)
Go to: Mac HD/Library/Internet Plugins
Verify that the Flash Player.plugin and flashplayer.xpt files are not present. If it they are, trash them.
Go to: Mac HD/Library/Internet Plugins/PepperFlashPlayer
Verify that PepperFlashPlayer.plugin and manifest.json files are not present. If it they are trash them.
Go to: Mac HD/Library/Application Support/Adobe/Flash Player
Verify that the Flash Player Install Manager folder does not exist. If it does, trash the whole folder
Go to: Mac HD/Users/YourUserID/Library/Internet Plug-Ins
Verify that Flash Player.plugin file is not present. If it is, trash it.
Empty the trash.
Make sure the 'Reopen windows when logging back in' check-box is NOT selected (This will "kill" all running processes)
Before launching any apps, mount the DMG and run the installer (double-click on the installer file to launch it).
During installation, when prompted for a password, this is the OS prompting for the password (e.g. your user Admin password), not Flash Player. See What userid & password do I need to install Flash Player? for assistance
BEFORE opening any Flash content, make sure Flash Player is enabled in the browser:
For Firefox, see Enable Flash Player for Firefox
For Safari, see Enable Adobe Flash Player for Safari
For Opera, see Enable Flash Player for Opera
Message was edited by: Maria Vargas - various edits throughout, including adding information for PPAPI plugin, what password to use, and links to enable Flash Player in the various browsers.