Https error Download images in the media library wordpress

Hello,

I encounter a problem downloading images as my site is https.

My website is a directory. there are two categories of users. They connect like this:

1 / administrator – It connects to the dashboard of WordPress.

2 / users – it connects to a form to write an ad. (he has no access to the WordPress dashboard).

Now the problem:

As the site is HTTP, administrator and user can log in and download images.

As the site is HTTPS, only the administrator can upload images (via dashboard wordpress).

The user can connect to the ad posting form. He can write his announcement, but can not download the images.

The download starts and stops. There is a message that says “an error occurred, please try again later”

Below is a copy of the screen:

https://drive.google.com/file/d/0B2r5LWQeXkZibEJtYjVRMmJTQWc/view?usp=sharing

If I make a network analysis, it appears that there is a problem of access to the “async- upload.php” file. Below is a copy of the screen:

https://drive.google.com/file/d/0B2r5LWQeXkZiTVdOVkFUeEduM0E/view?usp=sharing

Before posting, I made many tests:

– Disable all plugins.
– I tried PHP 5.3 and PHP 5.4
– I reinstall wordpress
– I contacted my host. He looked and said there is no problem on the server.

But the problem is still there. If I went back to HTTP, everything works fine. Users can upload images.

If I come with HTTPS, the site works correctly. All safety interlocks are green, but users can not download the images.

Someone has already encountered this problem? Can anyone give me a hint?

thank you in advance

https://wordpress.org/plugins/wordpress-https/