Everytime I want to access a page in admin, I get the following error in the top right corner: Notice at line 214 of X:\path-to-my-site\ncl\framework\dev\Deprecation.php.

Before this, I was having another problem with the CMS, everytime I wanted to change content or add widgets, I pressed saved and it would just give me an empty screen. After I refresh the page my changes wouldn't be made. I rad something about adding something like ?isDev=1 at the end of url and since that I get this error?

Does anybody have a clue about what's happening?

EDIT: isDev not really showing something that can help me solve the problem so I set isDev back to 0, i tried many thing but still get that empty screen