How to parse non-acsii utf8 string

[Nambers]

My data:

"{\"friend\":{\"type\":1,\"id\":1,\"groupid\":0,\"nickornamecard\":\"Eritque arcus\",\"botid\":1},\"message\":\"\xb0\xa1\",\"source\":\"{\\\"kind\\\":\\\"FRIEND\\\",\\\"botId\\\":1,\\\"ids\\\":[20751],\\\"internalIds\\\":[-1502808236],\\\"time\\\":1621222175,\\\"fromId\\\":1,\\\"targetId\\\":1,\\\"originalMessage\\\":[{\\\"type\\\":\\\"PlainText\\\",\\\"content\\\":\\\"\xb0\xa1\\\"}]}\",\"type\":2}"

My code:

json j;
    try {
        j = json::parse(tmp);
    } catch (json::parse_error &e) {
        logger->Error("json error, JNIEXPORT jstring JNICALL Java_tech_eritquearcus_miraicp_CPP_1lib_Event");
        logger->Error(j.dump());
        logger->Error(e.what());
        APIException("JSON error").raise();
        return returnNull();
    }

The error log:

json error, JNIEXPORT jstring JNICALL Java_tech_eritquearcus_miraicp_CPP_1lib_Event
2021-05-17 11:29:55 E/Bot: null
2021-05-17 11:29:55 E/Bot: [json.exception.parse_error.101] parse error at line 1, column 112: syntax error while parsing value - invalid string: ill-formed UTF-8 byte; last read: '"?
2021-05-17 11:29:55 E/Bot: json error

And I believe that the problem is in the message "\xb0\xa1", which is encoding from Chinese text, because when this message change to acsii code, this error will not happen.
That code look like the utf8 code of non acsii code(unicode)?
And my LLDB debugger print

UnicodeEncodeError: 'utf-8' codec can't encode characters in position 99-100: surrogates not allowed

What should I do to fix this error?
Thanks

[nlohmann]

The library only supports UTF-8. Please make sure your input is encoded in UTF-8.

[Nambers]

Oh yes, I believe that the data from breakpoint is as same as it's real text until I realize that is wrong.
And then, I use filesystem to ensure it is in utf8, like this

tmp = (const char *const)(std::filesystem::path(tmp).generic_u8string().c_str());

but it still not work

2021-05-17 14:16:44 E/Bot: [json.exception.parse_error.101] parse error at line 1, column 130: syntax error while parsing object - invalid literal; last read: '"{/"k'; expected '}'

Uh.. So what can i do?
Thanks for your response

[Nambers]

Oh I know the problem is, I will go check the json data, Thanks a lot lol

[Nambers]

Thankkkkkkk a lot,
eventually, i fix it, by using (const char *const)(std::filesystem::path(tmp).u8string().c_str()); to ensure the code is utf8