When you ask for url matching JSF servlet mapping, you get the FileNotFoundException and http code 500. This filter fixes it.

FileNotFoundFilter.java

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileNotFoundException;
import java.io.IOException;

/**
 * This filter interprets {@link FileNotFoundException} as HTTP status code <code>404</code>.
 *
 * @author banterCZ
 */
public class FileNotFoundFilter implements Filter {

    /**
     * {@inheritDoc}
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        //no code
    }

    /**
     * Interprets {@link FileNotFoundException} as HTTP status code <code>404</code>
     *
     * {@inheritDoc}
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        if (!(request instanceof HttpServletRequest) || !(response instanceof HttpServletResponse)) {
            throw new ServletException("FileNotFoundFilter just supports HTTP requests");
        }

        doFilter((HttpServletRequest) request, (HttpServletResponse) response, filterChain);
    }

    protected void doFilter(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws IOException, ServletException {
        try {
            filterChain.doFilter(request, response);
        } catch (FileNotFoundException e) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND, request.getRequestURI());
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void destroy() {
        //no code
    }

}