WordPress 4.0 Visual Editor not working.

Are you using any sort of caching plugin, or do you see a “Clear/Purge Cache” button in your Dashboard or admin bar? If so, would you please try clearing the cache?

If you aren’t using any sort of caching system, or clearing the cache made no difference, try downloading WordPress again and delete then replace your copies of everything except the wp-config.php file and the /wp-content/ directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them.

I’m having the exact same problem. I have disabled plugins and changed themes, and updated WordPress, but I still get the error with https://mydomain.com/wp-includes/js/tinymce/wp-tinymce.php?c=1&ver=4104-20140822

Any other ideas?

Did you do the re-installation as suggested above, complete with deleting the old files first?

I think we didn’t delete, we overwrote all files. Will try again tomorrow.

Excellent, please let us know how that goes!

Deleting the files and uploading a clean copy worked. Thank you, James!

You’re welcome!