If you're sure you've installed the latest version of Flash, take each of the following steps that you haven't already tried. After each step, relaunch Safari and test. For a "missing plug-in" error, start with Step 5.
1. If you're only having trouble with YouTube videos, sign in to your YouTube account and load this page. You may see a link with the text "Leave the HTML5 Trial." If so, click that link.
2. If you're getting a "blocked plug-in" error, then from the menu bar select
▹ System Preferences… ▹ Flash Player ▹ Advanced
and click Check Now. Quit and relaunch your browser.
3. Triple-click anywhere in the line below on this page to select it:
/Library/Internet Plug-Ins
Right-click or
control-click the highlighted text and select
Services ▹ Open
from the contextual menu.* A folder should open. Delete the following item, or anything with a similar name, if present:
Flash Player (failing).plugin
You may be prompted for your login password.
*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combinationcommand-C. In the Finder, select
Go ▹ Go to Folder...
from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.
4. Re-download and reinstall Flash. Download it from this page:
Never download a Flash update from anywhere else.
5. If you get a "
missing plug-in" error, select
Safari
▹
Preferences...
▹
Security
from the Safari menu bar and check the box marked
Enable plug-ins.
6. Select
Safari ▹ Preferences... ▹ Extensions
from the Safari menu bar. If any extensions are installed, disable them.
7. In the Safari preference window, select
Privacy ▹ Remove All Website Data
Close the window. Then select
▹ System Preferences… ▹ Flash Player ▹ Advanced
and click Delete All. Close the preference pane.
