Failed to parse HTML

[jerrymatjila]

Could someone please explain why this code is returning
"Failed to parse HTML: Could not determine tag type"

#include <iostream>
#include <cpr/cpr.h>
#include <pugixml.hpp>

int main() {
    cpr::Response response = cpr::Get(cpr::Url{"https://example.com"});
    if (response.status_code!= 200) {
        std::cerr << "Failed to fetch the webpage: " << response.text << std::endl;
        return 1;
    }

    pugi::xml_document doc;
    pugi::xml_parse_result result = doc.load_string(response.text.c_str());
    if (!result) {
        std::cout << "Failed to parse HTML: " << result.description() << std::endl;
        return 1;
    }
    return 0;
}

Any ideas how to fix it.

[jerrymatjila]

Found answer: Its caused by lowercase of doctype.