Video format or MIME type is not supported error in Firefox

If you are trying to play a video in Firefox browser but you receive Video format or MIME type is not supported error message on the player, these solutions are likely to help you. This problem occurs when your browser lacks certain functionality that is required to play that video.

Video format or MIME type is not supported

  1. Install, re-install Adobe Flash Player
  2. Enable JavaScript in the browser

1] Install or re-install Adobe Flash Player

Adobe Flash Player is the primary thing you need to play such video. Although you may be able to play similar videos without installing the Adobe Flash Player, you need to install that if you are getting such an error message. To install it, visit the official website.

In case, you already have it installed on your computer; you can try uninstalling and then re-installing it.

2] Enable JavaScript in the browser

There are many website admins who use JavaScript to show the player on their web pages. If you have disabled JavaScript in your Firefox browser, there is a high chance of getting this error message. Therefore, the simple solution is to enable JavaScript.

To do so, enter this in the address bar and hit the Enter button:


You need to click the I accept the risk button to go further. After that, look for:


Video format or MIME type is not supported

If the Value is set to False, just double-click on it to make it True. After that, reload the page and check if you can play the video or not.

Other things you could try is – Disable all the add-ons, clear web cache, update your browser and see that helps.

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Sudip is a student who loves to engage with the latest technology & gadgets. Apart from writing about all things technology, he is a Photoshop junkie and a football enthusiast.