Facing this issue in everything when I try to update articles, users or anything from the backend.
This issue started only after i moved the contents of frontend/web to the root and backend/web to a new folder admin on a shared host.
I put
public $enableCsrfValidation = false;
in the controller and tht clears out this error but I am not sure if I want to do this on each controller now. Any suggestions or help?