When uploading a large file via the Media uploader, I get the infamous HTTP Error problem. I also have the following in the Chrome console:
POST http://www.nameofsite.co/wp-admin/async-upload.php 500 (Internal Server Error)
The file is actually uploaded and appears in the uploads directory. I have tried all suggestions in the question linked above.
Wordpress version is 4.0.1 on 1&1 UK shared hosting
With all plugins disabled, the error does not happen. If I enable, for example, revolution slider, the error occurs. However, I believe more than one plugin or a combination of plugins might be causing the problem. The fact that I am able to upload large images with all plugins disabled leads me to believe that a function or functions within certain plugins is interfering with async upload and that this is not a server config issue.
Other plugins causing the issue - uploadcare, fusion-core