Self sign certificate programatically - c++

Question

I'm trying to build a fake HTTPS server (like mitmproxy), so I made an SSL "sign" function. after generating and installing the certificate on my system I got the error: "NET::ERR_CERT_AUTHORITY_INVALID"/ "MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT".
The code looks like
static bool generateX509(const std::shared_ptr<CA>& ca, SSL *ssl, const char * domain)
{
auto ca_cert = ca->ca_crt.get();
auto ca_pkey = ca->ca_key.get();
// --- cert generation ---
std::unique_ptr<X509, void (*)(X509 *)> cert { X509_new(), X509_free };
X509_set_notBefore(cert.get(), X509_get_notBefore(ca_cert));
X509_set_notAfter(cert.get(), X509_get_notAfter(ca_cert));
X509_set_serialNumber(cert.get(), X509_get_serialNumber(ca_cert));
X509_set_pubkey(cert.get(), X509_get_pubkey(ca_cert));
X509_set_version(cert.get(), 2);
const unsigned char country[] = "RU";
const unsigned char company[] = "MyCompany, PLC";
X509_name_st* name = X509_get_subject_name(cert.get());
X509_NAME_add_entry_by_txt(name, "C", MBSTRING_ASC, country, -1, -1, 0);
X509_NAME_add_entry_by_txt(name, "O", MBSTRING_ASC, company, -1, -1, 0);
X509_NAME_add_entry_by_txt(name, "CN", MBSTRING_ASC, (const unsigned char *)domain, -1, -1, 0);
X509_set_issuer_name(cert.get(), name);
X509_EXTENSION *Extension;
char Buffer[512];
// Format the value
sprintf (Buffer, "DNS:%s", domain);
Extension = X509V3_EXT_conf_nid (nullptr, nullptr, NID_subject_alt_name, Buffer);
if (Extension) {
X509_add_ext (cert.get(), Extension, -1);
X509_EXTENSION_free (Extension);
}
X509_sign(cert.get(), ca_pkey, EVP_sha256()); // some hash type here
SSL_use_certificate(ssl, cert.get());
SSL_use_PrivateKey(ssl, ca_pkey);
return true;
}
What i missing?
How to resolve this error