Why is WordPress stripping out the div with a CSS class "error"?

WordPress might be "stripping out" or modifying the HTML in various ways for a couple of reasons, and it might not necessarily be specifically targeting a div with a class of "error." Here are a few possibilities:

1. HTML Filtering and Security: WordPress often employs security measures to prevent malicious code from being executed. It may use HTML filtering functions that strip out certain elements or attributes deemed risky, such as script tags, inline event handlers, etc.

2. Editor Behavior: If you are using the WordPress editor (Gutenberg or Classic Editor), it might automatically clean up or modify the HTML code for better consistency and compatibility. In some cases, it may not preserve certain HTML elements or classes if they are not recognized or considered standard.

3. Theme or Plugin Modifications: Themes and plugins can also influence the rendering of HTML. Some themes or plugins might have custom filters or functions that modify the content before it's displayed.

To troubleshoot the issue:

• Inspect the HTML Output: Use your browser's developer tools to inspect the actual HTML output. Check if the div with the "error" class is present in the initial server response. If it is, then something might be modifying it after the fact.

• Review Theme and Plugin Code: Check if your theme or any plugins you're using have functions or filters that could affect the output. Review their documentation or support forums for any relevant information.

• Disable Plugins/Themes: Temporarily disable plugins and switch to a default WordPress theme to see if the issue persists. This can help identify whether the problem is related to a specific theme or plugin.

• Custom Code: If you've added custom code or modifications, review them to ensure they are not inadvertently altering the HTML output.

If you find that WordPress is indeed modifying the HTML in an undesirable way, you may need to implement workarounds or adjust settings to achieve the desired output. Keep in mind that certain modifications are in place for security and consistency reasons, so be cautious when making changes.