Elementor loads many widgets, styles, and scripts while you edit a page. When PHP does not have enough memory, the script stops and shows a fatal error. The error appears because the configured memory limit is lower than the amount required by Elementor and any additional plugins or large page content.
The limit is defined by the server’s PHP settings and can be overridden by WordPress constants. If the server enforces a hard cap, WordPress is unable to increase the limit, and Elementor runs out of memory during save or render operations.