When uploading HTTP Error or other kind of errors.

Hey I am having a horibble problem.

Whenever i try to upload images, no matter if i am using Multi File uploader or single file uploader i always get error messages. This didn’t happen before. I used to previously have a WordPress installation on the same domain and same webserver which i deleted, then it was working fine and image upload was working fine too.

Now i simply reinstalled WordPress on same server/domain, but it gives me those image uploading errors. No matter which image i upload. JPG or PNG, no matter what resolution, name or colors. I just always get it.

Somewhere i read that some plugins may cause it, but i uninstalled few less common plugins, but the error was still there. I even upgraded to PHP 7.0. And the other plugins that i have enabled, i have used them all in this same combination on my other WordPress Installations/Sites and they have never caused any problems before.

What causes this anoyying error? Are the developers of their plugins/WordPress so incompetent that they cannot fix those simple errors?

Someone please give me a advice what to do.