Zoho Invoice API Error {"error":"invalid_client"} while requesting for token

Question

While accessing Zoho api to get the token I'm getting the following error:

{"error":"invalid_client"}

Step 1: I'm requesting for Auth Code and the auth code is returned successfully.

This is the API I'm using. https://accounts.zoho.com/oauth/v2/auth?scope=xxx&client_id=yyyyy&state=zzzz&response_type=code&redirect_uri=pppppp&access_type=offline

Step 2: Token Request With the Auth Code obtained in Step-1 I'm doing a post request for the token at that time only I'm getting the below exception.

var authTokenRequestData = new
{
    code= code,
    client_id= _clientId,
    client_secret =_clientSecret,
    redirect_uri = _redirectUri,
    grant_type = "authorization_code"
};


var data = new StringContent(JsonConvert.SerializeObject(authTokenRequestData), Encoding.UTF8, "application/json");
    
var url = "https://accounts.zoho.com/oauth/v2/token";

string result = "";

using (var client = new HttpClient())
    {
        var response = await client.PostAsync(url, data);
        result = await response.Content.ReadAsStringAsync();
    }

It's giving me the exception

{error:invalid_client}

I've verified my client_id and client_secret. It's correct only.

It's Server-Based-Application client I've registered.

Any help is highly appreciated on this.

This error was happening for me in Insomnia API testing app and in the end I had to write curl code in PHP to do it manually to get the tokens...Idk why Insomnia was returning the error even though I was sending it as POST with the correct `Content-Type`. — Uriahs Victor, Aug 17 '22 at 22:41

score 10 · Answer 1 · answered Feb 03 '22 at 13:30

There could be one more reason for this issue.

{"error":"invalid_client"}

Check if you're using the correct domain. (.in .com or...)

For example, you're using .in instead of .com or vice-versa

In my case when I was using .in domain but my domain was .com I was getting the same error {"error":"invalid_client"}

I was using this:

var url = "https://accounts.zoho.in/oauth/v2/token";

I replaced it as below and that solved my issue.

var url = "https://accounts.zoho.com/oauth/v2/token";

score 2 · Answer 2 · answered Jan 18 '22 at 06:51

I could solve this issue by changing the request Content-Type

"Content-Type", "application/x-www-form-urlencoded"

Complete code is as follows:

string _domain = ".in"; /*Ensure you're using the correct .com or .in domain*/
var url = "https://accounts.zoho"+ _domain + "/oauth/v2/token";

string result = "";

using (var client = new HttpClient())
    {
        var data = new Dictionary<string, string>
        {
            { "Content-Type", "application/x-www-form-urlencoded" },
            { "code", code },
            { "client_id", _clientId },
            { "client_secret", _clientSecret },
            { "redirect_uri", _redirectUri },
            { "grant_type", "authorization_code" },
            { "access_type", "offline" }
         };

var response = await client.PostAsync(url, new FormUrlEncodedContent(data));
result = await response.Content.ReadAsStringAsync();
    }

Zoho Invoice API Error {"error":"invalid_client"} while requesting for token

2 Answers2