When working in the Content Editor and clicking the Open Media Library button of the Image field, the user may expect seeing a dialog box that allows choosing an image.
Instead, the user is switched to the Media Library or receives the following error:
The selected item could not be found. It may have been deleted by another user. Select another item.
The cause of this behavior is that the purpose of the Open Media Library button is not to open a dialog box to select an image, but to open the Media Library to edit the currently selected media item.