Using virtual="file.html" but the path is wrong, or using file="..." incorrectly. Fix: Use virtual="relative/path/to/file.html" . Remember: virtual starts from the document root; file starts from the current directory.
The extension is a unique web file format that stands for Server-Parsed HTML . While it functions similarly to standard HTML, it includes a powerful layer of Server Side Includes (SSI) , allowing web developers to inject dynamic content—like shared headers, footers, or navigation menus—across multiple pages from a single source file. view shtml best