I updatet a wordpress multisite installation to the newest version 4.9. After the update, the media gallery in the backend is not showing any images. Its blank. The images are still in the uploads folder and i deactivated all plugins.

When i open the media gallery i get the following errors inside the console:

ReferenceError: MediaElementPlayer is not defined
TypeError: $(...).not(...).filter(...).mediaelementplayer is not a function

I updatet a wordpress multisite installation to the newest version 4.9. After the update, the media gallery in the backend is not showing any images. Its blank. The images are still in the uploads folder and i deactivated all plugins.

When i open the media gallery i get the following errors inside the console:

ReferenceError: MediaElementPlayer is not defined
TypeError: $(...).not(...).filter(...).mediaelementplayer is not a function

• javascript
• wordpress

• Same here! Just updated to 4.9 and now cannot add any media to my posts. – Benjamin Commented Nov 17, 2017 at 14:56

2 Answers 2

It's a new known bug, see here. They are working on a solution.

For the moment I have changed language in WordPress settings from de-DE-formal ("Deutsch (Sie)") to de-DE ("Deutsch").

Which language have you activated? I had the same problem, but in my case there where also the error:

TypeError: Language code must have format 2-3 letters and. optionally, hyphen, underscore followed by 2 more letters

In my case, the language "de_DE_formal" (Deutsch (Sie)) was activated. After I set the language to the "de_DE" (Deutsch) the error was gone.