We review each new stable Firefox release here on Ghacks Technology News, and one recurring theme that we come across is that at least some users report issues with Adobe's Flash Player after they have updated to the latest version of Firefox.
While many users do not experience any issues, some do and it can be a frustrating experience, especially if you do not really know where to start troubleshooting the issue to resolve it.
Both Firefox and Flash are complex programs, which means that there is not a single solution that fixes the issue for all users experiencing crashes or hangs.
The following list may help resolve the issues that you are experiencing. Lets get started.
Make sure Flash is up to date
If you are running an older version of Flash, you may experience crashes or hangs that are resolved in newer versions. This is not always the case, and it can very well happen that upgrading to the latest version causes the issues to appear on your system for the first time.
Generally speaking, it is better to run the latest Flash version than an outdated version. The reason here is mostly security, as older versions are vulnerable to attacks that got fixed in the updated versions.
Check to see if your Flash version is up to date on Mozilla's Plugin Check website.
You can download the latest Flash Player version from Adobe.
If that version is causing issues for you, you may want to try a beta version of an upcoming version of Adobe Flash instead.
What I do not suggest is to downgrade due to the security implications that come along with it.
Enable Click-to Play
The Flash plugin is enabled by default in Firefox, which means that it can be used by any website you load in the browser.
By enabling click-to play, you prevent that Flash can be used on all sites but the ones that you allow it to run on. This prevents the loading of Flash ads, videos, or other Flash contents on the majority of sites, which in turn improves stability.
You can whitelist specific sites easily, here is how that is done.
Use one browser to play Flash contents, and Firefox for the rest
Okay this may not work for all users or be desired by most, but if you experience a lot of hangs or crashes in Firefox that are related to Flash, you may want to consider using a different browser to play Flash contents.
This works well if you only visit a couple of sites that require Flash, maybe sites like YouTube, Kongregate or Armorgames for example.
The best browser in my opinion for this on most systems is Google Chrome, as it comes with a native version of Flash. If you use Windows 8, you may also use Internet Explorer as it comes with its own native Flash version as well.
If you only use YouTube, switch to HTML5 video
If YouTube is your only destination on the Internet that requires Flash to play videos, you may want to switch to HTML5 video instead to avoid the crashes and disable Flash Player in your browser or even uninstall it.
Most videos will work just fine if you make the switch, but some may not, so keep that in mind.
To switch, go here and click on the request the HTML5 player button.
Disable hardware acceleration
Flash uses hardware acceleration which is designed to improve performance when Flash Player is being used on your system.
It can cause issues on the other hand, and one way to find out if hardware acceleration is responsible for that, is to disable it to see if crashes or hangs stop or continue.
Disable Protected Mode
Protected Mode was added to Flash Player 11.3 and later on Windows Vista and newer versions of the Microsoft Windows operating system.
It has been designed to improve the security of the system by limiting the impact of attacks launched from malicious Flash files.
You can try and disable Protected Mode on your system to see if it resolves the issue. We have published an extensive guide on how to do so here.
It used to be easy to disable plugin-container.exe, the file that is run whenever you run plugins such as Flash. I have published a guide on how to disable the feature in newer versions of Firefox.
It requires the creation of a new user or system environment variable. Check out the full guide here.
Clear Windows Prefetch files
While I was not able to test the following solution myself, some users have reported that it resolved all Flash issues that they were experiencing on their PC.
The user who came up with the solution suggested to clear two Windows prefetch files every 15 minutes:
You can either do so manually, or create a task in the Windows Task Scheduler instead to do so automatically for you.
I suggest you try the solution manually first to see if it resolves the issue. If it does, implement an automated solution. The user who posted the solution has created a script that you can run for that purpose.
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