Blank page after every action, deactivating plugins doesnt work

Hello!

Since a while (i dont remember doing some changes at the time) I get blank pages when I try to acces my website with www. in front of my url. Without it does work.

Next to that, I can’t add photos in the post, only one for the cover of the post.

When I try to preview, schedule, save or post a post I get a blank page too.

I already deactivated all the plug ins, but I still have this problem.

Hopefully somebody can help!

Edit: Turns out I had to update my php to a higher version, I found out myself, maybe this will help somebody else in the future!