Mozilla has blocked all versions of Flash in Firefox due to third zero-day found in Flash Player by Hacking Team. Google Chrome too blocks older versions of Flash automatically and shows this error message for a flash content page ‘Adobe Flash was blocked because it is out of date’ and offers ‘Update plugin’ and ‘Run this time’ options.
Update plugin won’t update the plugin, instead it takes you to the Chrome help page, clicking ‘Run this time’ is not recommended.
NEWS UPDATE Nov 2, 2016: Chrome 54: Google is working to fix Flash Player 23’s Couldn’t load Plugin Issue
Fix Chrome’s ‘Adobe Flash Player has been blocked because it is out of date’ Error
I. Ensure you’re using the latest version of Chrome as of this date (latest version number is 43.0.2357.132). If you can’t update Chrome browser, run Google Software Removal Tool, which corrects the auto-update issue. Here is the link for it: SRT.
II. How to update Pepper Flash in Chrome
1. Make sure Pepper Flash Google Chrome uses is also up-to-date, currently it has version number:18.104.22.168. For this, visit chrome://components page
2. Under Pepper_ flash, click ‘check for update’, latest flash update will be downloaded and installed, status reflects that change.
Note: This is the best way to update flash in older versions of Chrome.
3. If that doesn’t help, confirm you’re using only PPAPI Flash, not NPAPI Flash. For that, visit chrome://plugins page, click on ‘+Details’ to expand, ensure only one Adobe Flash Player is listed and enabled, and its type should be shown as PPAPI (out-of -process).