The editor stops loading because Elementor cannot add a control to its stack. The process aborts when a control class is missing, duplicated, or registered with an outdated method. Elementor expects each control to have a unique ID and to be loaded before the registration hook runs.
When the registration fails, Elementor throws a PHP warning or fatal error. The warning appears in the debug log and the browser console shows a short message. The error prevents default widgets from rendering their settings panels.
Typical triggers include old code that still calls the private _register_controls function, third‑party add‑ons that register the same control ID, or a PHP version that does not support the syntax used by the control class. Corrupted core files or mismatched Elementor and Elementor Pro versions also produce the same symptom.