If an HTML page no longer validates after changing the DOCTYPE declaration, what should be done to rectify this?

When a DOCTYPE declaration is changed and it results in the HTML page no longer validating, the most straightforward approach is to fix the code so that it conforms to the new DOCTYPE specification. This is typically the case when transitioning to a new version like HTML5, which has different rules and structures compared to older versions like HTML 4.01.

By choosing to adjust the code to meet the requirements set by the new DOCTYPE, developers ensure that they are utilizing the latest standards for web development, which can improve compatibility and features in modern browsers. HTML5, for example, introduces new elements, attributes, and handling of content that need to be properly implemented for the page to validate successfully. This approach also promotes learning and adapting to modern web practices.

Reverting back to an older DOCTYPE can stifle progress and limit the features and capabilities of the site. Using GUI editors might provide a quick fix but can introduce more issues or not address the underlying problems in the code. Recreating the page from scratch is often unnecessary and inefficient; instead, it is preferable to update and validate the existing code to align with the current standards.

Therefore, adapting the code to ensure compliance with HTML5, if that's the new DOCTYPE, is the most