Select your server or the specific website in the left connections pane. In the features view, double-click on . Look for SSINC-shtml in the list.

If you want to use SSI inside normal .html files (not recommended for performance reasons, but possible), add: AddOutputFilter INCLUDES .html Use code with caution. 2. Fixing Common SSI Syntax Errors

Ensure there is an active mapping for *.shtml pointing to the ServerSideIncludeModule . Verifying the Fix

stands for Server Side Include HyperText Markup Language . A file with the .shtml extension is a standard HTML file that contains server-side instructions known as Server Side Includes (SSI) .

Ensure the included files (e.g., header.html ) are also set to 644 . Fix 3: Check for Correct SSI Syntax

The included file must be readable by the web server user (e.g., www-data ).

For those maintaining very old IIS 5.0 or IIS 6.0 servers, there is a specific bug related to the JRUN ISAPI filter. The JRUN filter, used for ColdFusion and other Java applications, would sometimes intercept .shtml requests and prevent them from being passed to the correct handler, returning a 404 - Not Found error.

Or, if the server is running a vulnerable version of the mod_include module (common in older Apache versions), simply viewing a maliciously crafted SHTML file could allow the execution of system commands (Remote Code Execution - RCE).

If you use Linux with SELinux enabled, verify the security contexts allow the web server to read the included files. Run chcon -t httpd_sys_content_t on your web directory if the server logs show permission denied errors despite correct CHMOD settings. 4. Resolve Syntax Errors in SSI Directives

AddType text/html .html .htm .shtml AddOutputFilter INCLUDES .html .htm .shtml Use code with caution.

To avoid View SHTML errors in the future, follow these best practices:

Web servers reject SSI execution if file permissions are configured too loosely or tightly. This security measure prevents unauthorized script execution. Permissions Check