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System.Text.Json.JsonException: The JSON value could not be converted

I'm using Ubuntu and dotnet 3.1, running vscode's c# extension.
I need to create a List from a JSON file, my controller will do some calculations with this model List that I will pass to it
So, here is my code and the error I'm getting.
First, I thought my error was because at model my attributes were char and C#, for what I saw, cannot interpret double-quotes for char, it should be single quotes. Before losing time removing it, I just changed my type declarations to strings and it's the same error.
Can someone help me?
ElevadorModel
using System.Collections.Generic;
namespace Bla
{
public class ElevadorModel
{
public int andar { get; set; }
public string elevador { get; set; }
public string turno { get; set; }
}
}
Program.cs:
class Program
{
static void Main(string[] args)
{
var path = "../input.json";
string jsonString;
ElevadorModel elevadoresModel = new ElevadorModel();
jsonString = File.ReadAllText(path); //GetType().Name = String
Console.WriteLine(jsonString); //WORKS
elevadoresModel = JsonSerializer.Deserialize<ElevadorModel>(jsonString);
}
JSON:

Your input json has an array as the base token, whereas you're expecting an object. You need to change your deserialization to an array of objects.
var elevadoresModels = JsonSerializer.Deserialize<List<ElevadorModel>>(jsonString);
elevadoresModel = elavoresModels.First();

Your input JSON is an array of models, however you're trying to deserialize it to a single model.
var models = JsonSerializer.Deserialize<List<ElevadorModel>>(jsonString);

This is also a problem in Blazor-Client side. For those calling a single object
e.g ClassName = await Http.GetFromJsonAsync<ClassName>($"api/ClassName/{id}");
This will fail to Deserialize. Using the same System.Text.Json it can be done by:
List<ClassName> ListName = await Http.GetFromJsonAsync<List<ClassName>>($"api/ClassName/{id}");
You can use an array or a list. For some reason System.Text.Json, does not give errors and it is successfully able Deserialize.
To access your object, knowing that it is a single object use:
ListName[0].Property
In your case the latter solution is fine but with the path as the input.

In my case, I was pulling the JSON data to deserialize out of an HTTP response body. It looked like this:
var resp = await _client.GetAsync($"{endpoint}");
var respBody = await resp.Content.ReadAsStringAsync();
var listOfInstances = JsonSerializer.Deserialize<List<modelType>>(respBody);
And the error would show up. Upon further investigation, I found the respBody string had the JSON base object (an array) wrapped in double quotes...something like this:
"[{\"prop\":\"value\"},...]"
So I added
respBody = respBody.Trim('\"');
And the error changed! Now it was pointing to an invalid character '\'.
I changed that line to include
respBody = respBody.Trim('\"').Replace("\\", "");
and it began to deserialize perfectly.
For reference:
var resp = await _client.GetAsync($"{endpoint}");
var respBody = await resp.Content.ReadAsStringAsync();
respBody = respBody.Trim('\"').Replace("\\", "");
var listOfInstances = JsonSerializer.Deserialize<List<modelType>>(respBody);

Adding object to JSON file

I'm creating a software on which I added a profiles feature where the user can create profile to load his informations faster. To store these informations, I'm using a JSON file, which contains as much objects as there are profiles.
Here is the format of the JSON file when a profile is contained (not the actual one, an example) :
{
"Profile-name": {
"form_email": "example#example.com",
//Many other informations...
}
}
Here is the code I'm using to write the JSON and its content :
string json = File.ReadAllText("profiles.json");
dynamic profiles = JsonConvert.DeserializeObject(json);
if (profiles == null)
{
File.WriteAllText(jsonFilePath, "{}");
json = File.ReadAllText(jsonFilePath);
profiles = JsonConvert.DeserializeObject<Dictionary<string, Profile_Name>>(json);
}
profiles.Add(profile_name.Text, new Profile_Name { form_email = form_email.Text });
var newJson = JsonConvert.SerializeObject(profiles, Formatting.Indented);
File.WriteAllText(jsonFilePath, newJson);
profile_tr.Nodes.Add(profile_name.Text, profile_name.Text);
debug_tb.Text += newJson;
But when the profiles.json file is completely empty, the profile is successfully written, but when I'm trying to ADD a profile when another one already exists, I get this error :
The best overloaded method match for 'Newtonsoft.Json.Linq.JObject.Add(string, Newtonsoft.Json.Linq.JToken)' has some invalid arguments on the profiles.Add(); line.
By the way, you can notice that I need to add {} by a non-trivial way in the file if it's empty, maybe it has something to do with the error ?
The expected output would be this JSON file :
{
"Profile-name": {
"form_email": "example#example.com",
//Many other informations...
},
"Second-profile": {
"form_email": "anotherexample#example.com"
//Some other informations...
}
}

Okay so I found by reading my code again, so I just replaced dynamic profiles = JsonConvert.DeserializeObject(json); to dynamic profiles = JsonConvert.DeserializeObject<Dictionary<string, Profile_Name>>(json);.
But it still don't fix the non-trivial way I use to add the {} to my file...

The object the first DeserializeObject method returns is actually a JObject, but below you deserialize it as a Dictionary. You shouldn't be mixing the types, choose either one.
If you use the JObject then to add objects you need to convert them to JObjects:
profiles.Add(profile_name.Text, JObject.FromObject(new Profile_Name { form_email = form_email.Text }));
In both cases, when the profile is null you just need to initialize it:
if (profiles == null)
{
profiles = new JObject(); // or new Dictionary<string, Profile_Name>();
}

Converting large httpresponse stream to a JSON string?

Question Background:
Update:
I'm still not sure how to go about extracting the relevant information from this response. I have tried setting my response type to JSON but still receive the response as shown below. I have taken into account what has been said in regards to using NameValueCollection but still cant see how this will help with such a large response. Ideally I'd like this mapped to an object structure of some kind, it dosen't necessarily have to be JSON.
Question:
I'm currently using the PayPal Api 'ExpressCheckout' method to allow users to pay for items on my test site. A HTTP response from the API provides a large response containing key information I need to extract - such as the buyers address, if the payment was succesful etc.
The Issue:
Currently I'm stuck on how to work with the response. Ideally I'd convert the data to a JSON string then use Newtonsoft to map the data to C# classes thus allowing easy access to the data. Here is an example of the Httpresponse:
TOKEN=EC%2XXXXXXXXXXXXXXXXXR&BILLINGAGREEMENTACCEPTEDSTATUS=0&CHECKOUTSTATUS=PaymentActionNotInitiated&TIMESTAMP=2015%2d01%2d02T21%3a11%3a30Z&CORRELATIONID=ab184fdba7a30&ACK=Success&VERSION=88%2e0&BUILD=14443165&EMAIL=test%40aol%2ecom&PAYERID=3XXXXXXXXXX4N&PAYERSTATUS=verified&BUSINESS=Test%20Biz%27s%20Test%20Store&FIRSTNAME=Joe&LASTNAME=King&COUNTRYCODE=GB&SHIPTONAME=Joe%20King%27s%20Test%20Store&SHIPTOSTREET=1%20Main%20Terrace&SHIPTOCITY=Wolverhampton&SHIPTOSTATE=West%20Midlands&SHIPTOZIP=W12%204LQ&SHIPTOCOUNTRYCODE=GB&SHIPTOCOUNTRYNAME=United%20Kingdom&ADDRESSSTATUS=Confirmed&CURRENCYCODE=GBP&AMT=15%2e56&ITEMAMT=15%2e56&SHIPPINGAMT=0%2e00&HANDLINGAMT=0%2e00&TAXAMT=0%2e00&INSURANCEAMT=0%2e00&SHIPDISCAMT=0%2e00&L_NAME0=ItemOne&L_QTY0=4&L_TAXAMT0=0%2e00&L_AMT0=3%2e89&L_ITEMWEIGHTVALUE0=%20%20%200%2e00000&L_ITEMLENGTHVALUE0=%20%20%200%2e00000&L_ITEMWIDTHVALUE0=%20%20%200%2e00000&L_ITEMHEIGHTVALUE0=%20%20%200%2e00000&PAYMENTREQUEST_0_CURRENCYCODE=GBP&PAYMENTREQUEST_0_AMT=15%2e56&PAYMENTREQUEST_0_ITEMAMT=15%2e56&PAYMENTREQUEST_0_SHIPPINGAMT=0%2e00&PAYMENTREQUEST_0_HANDLINGAMT=0%2e00&PAYMENTREQUEST_0_TAXAMT=0%2e00&PAYMENTREQUEST_0_INSURANCEAMT=0%2e00&PAYMENTREQUEST_0_SHIPDISCAMT=0%2e00&PAYMENTREQUEST_0_INSURANCEOPTIONOFFERED=false&PAYMENTREQUEST_0_SHIPTONAME=Joe%20King%27s%20Test%20Store&PAYMENTREQUEST_0_SHIPTOSTREET=1%20Main%20Terrace&PAYMENTREQUEST_0_SHIPTOCITY=Wolverhampton&PAYMENTREQUEST_0_SHIPTOSTATE=West%20Midlands&PAYMENTREQUEST_0_SHIPTOZIP=W12%204LQ&PAYMENTREQUEST_0_SHIPTOCOUNTRYCODE=GB&PAYMENTREQUEST_0_SHIPTOCOUNTRYNAME=United%20Kingdom&PAYMENTREQUEST_0_ADDRESSSTATUS=Confirmed&L_PAYMENTREQUEST_0_NAME0=ItemOne&L_PAYMENTREQUEST_0_QTY0=4&L_PAYMENTREQUEST_0_TAXAMT0=0%2e00&L_PAYMENTREQUEST_0_AMT0=3%2e89&L_PAYMENTREQUEST_0_ITEMWEIGHTVALUE0=%20%20%200%2e00000&L_PAYMENTREQUEST_0_ITEMLENGTHVALUE0=%20%20%200%2e00000&L_PAYMENTREQUEST_0_ITEMWIDTHVALUE0=%20%20%200%2e00000&L_PAYMENTREQUEST_0_ITEMHEIGHTVALUE0=%20%20%200%2e00000&PAYMENTREQUESTINFO_0_ERRORCODE=0
If anyone could give me an easy way to map this data to a C# object that would be great.

Is there any specific reason why you want it in JSON format? If its not requirement and if you can live with key value pair then here is one way you can process response as key value pair.
public partial class Form1 : Form
{
Dictionary<string, string> processedResponse = null;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
string rawResponse = "TOKEN=EC%2XXXXXXXXXXXXXXXXXR&BILLINGAGREEMENTACCEPTEDSTATUS=0&CHECKOUTSTATUS=PaymentActionNotInitiated&TIMESTAMP=2015%2d01%2d02T21%3a11%3a30Z&CORRELATIONID=ab184fdba7a30&ACK=Success&VERSION=88%2e0&BUILD=14443165&EMAIL=test%40aol%2ecom&PAYERID=3XXXXXXXXXX4N&PAYERSTATUS=verified&BUSINESS=Test%20Biz%27s%20Test%20Store&FIRSTNAME=Joe&LASTNAME=King&COUNTRYCODE=GB&SHIPTONAME=Joe%20King%27s%20Test%20Store&SHIPTOSTREET=1%20Main%20Terrace&SHIPTOCITY=Wolverhampton&SHIPTOSTATE=West%20Midlands&SHIPTOZIP=W12%204LQ&SHIPTOCOUNTRYCODE=GB&SHIPTOCOUNTRYNAME=United%20Kingdom&ADDRESSSTATUS=Confirmed&CURRENCYCODE=GBP&AMT=15%2e56&ITEMAMT=15%2e56&SHIPPINGAMT=0%2e00&HANDLINGAMT=0%2e00&TAXAMT=0%2e00&INSURANCEAMT=0%2e00&SHIPDISCAMT=0%2e00&L_NAME0=ItemOne&L_QTY0=4&L_TAXAMT0=0%2e00&L_AMT0=3%2e89&L_ITEMWEIGHTVALUE0=%20%20%200%2e00000&L_ITEMLENGTHVALUE0=%20%20%200%2e00000&L_ITEMWIDTHVALUE0=%20%20%200%2e00000&L_ITEMHEIGHTVALUE0=%20%20%200%2e00000&PAYMENTREQUEST_0_CURRENCYCODE=GBP&PAYMENTREQUEST_0_AMT=15%2e56&PAYMENTREQUEST_0_ITEMAMT=15%2e56&PAYMENTREQUEST_0_SHIPPINGAMT=0%2e00&PAYMENTREQUEST_0_HANDLINGAMT=0%2e00&PAYMENTREQUEST_0_TAXAMT=0%2e00&PAYMENTREQUEST_0_INSURANCEAMT=0%2e00&PAYMENTREQUEST_0_SHIPDISCAMT=0%2e00&PAYMENTREQUEST_0_INSURANCEOPTIONOFFERED=false&PAYMENTREQUEST_0_SHIPTONAME=Joe%20King%27s%20Test%20Store&PAYMENTREQUEST_0_SHIPTOSTREET=1%20Main%20Terrace&PAYMENTREQUEST_0_SHIPTOCITY=Wolverhampton&PAYMENTREQUEST_0_SHIPTOSTATE=West%20Midlands&PAYMENTREQUEST_0_SHIPTOZIP=W12%204LQ&PAYMENTREQUEST_0_SHIPTOCOUNTRYCODE=GB&PAYMENTREQUEST_0_SHIPTOCOUNTRYNAME=United%20Kingdom&PAYMENTREQUEST_0_ADDRESSSTATUS=Confirmed&L_PAYMENTREQUEST_0_NAME0=ItemOne&L_PAYMENTREQUEST_0_QTY0=4&L_PAYMENTREQUEST_0_TAXAMT0=0%2e00&L_PAYMENTREQUEST_0_AMT0=3%2e89&L_PAYMENTREQUEST_0_ITEMWEIGHTVALUE0=%20%20%200%2e00000&L_PAYMENTREQUEST_0_ITEMLENGTHVALUE0=%20%20%200%2e00000&L_PAYMENTREQUEST_0_ITEMWIDTHVALUE0=%20%20%200%2e00000&L_PAYMENTREQUEST_0_ITEMHEIGHTVALUE0=%20%20%200%2e00000&PAYMENTREQUESTINFO_0_ERRORCODE=0";
//Process response
processedResponse = ProcessResponse(rawResponse);
//Use received data e.g.
//Get First name
string fName = GetRecordValue("FIRSTNAME");
//Get Last name
string lName = GetRecordValue("LASTNAME");
}
private Dictionary<string,string> ProcessResponse(string response)
{
Dictionary<string, string> responseData = new Dictionary<string, string>();
if(!string.IsNullOrWhiteSpace(response))
{
string[] firstPass = response.Split(new char[] { '&' });
foreach(string pair in firstPass)
{
string[] secondPass = pair.Split(new char[] { '=' });
if(secondPass!=null && secondPass.Length>0)
{
responseData.Add(secondPass[0].Trim(), secondPass[1].Trim());
}
}
}
return responseData;
}
private string GetRecordValue(string record)
{
string recordValue = null;
if(processedResponse!=null)
{
if(!string.IsNullOrWhiteSpace(record) && processedResponse.ContainsKey(record))
{
recordValue= processedResponse[record];
}
}
return recordValue;
}
}

Still unsure what's the problem with dealing with it as a NameValueCollection.
E.g.
//NameValueCollection
//or use HttpUtility.ParseQueryString(some_string_of_names_values)
var foo = Request.QueryString;
var bar = foo["FIRSTNAME"]; //based on above this is "Joe"
Update:
It is response string which is being processed here and not request hence you wont be able to retrieve details using Request.QueryString
As stated in comments:
string rawResponse = "TOKEN=EC%2XXXXXXXXXXXXXXXXXR&BILLINGAGREEMENTACCEPTEDSTATUS=0&CHECKOUTSTATUS=PaymentActionNotInitiated&TIMESTAMP=2015%2d01%2d02T21%3a11%3a30Z&CORRELATIONID=ab184fdba7a30&ACK=Success&VERSION=88...."
var foo = HttpUtility.ParseQueryString(rawResponse); //NameValueCollection
var bar = foo["FIRSTNAME"]; //Joe

Unexpected character encountered while parsing value

Currently, I have some issues. I'm using C# with Json.NET. The issue is that I always get:
{"Unexpected character encountered while parsing value: e. Path '', line 0, position 0."}
So the way I'm using Json.NET is the following. I have a Class which should be saved. The class looks like this:
public class stats
{
public string time { get; set; }
public string value { get; set; }
}
public class ViewerStatsFormat
{
public List<stats> viewerstats { get; set; }
public String version { get; set; }
public ViewerStatsFormat(bool chk)
{
this.viewerstats = new List<stats>();
}
}
One object of this class will be filled and saved with:
File.WriteAllText(tmpfile, JsonConvert.SerializeObject(current), Encoding.UTF8);
The saving part works fine and the file exists and is filled. After that the file will be read back into the class with:
try
{
ViewerStatsFormat current = JsonConvert.DeserializeObject<ViewerStatsFormat>(tmpfile);
//otherstuff
}
catch(Exception ex)
{
//error loging stuff
}
Now on the current= line comes the exception:
{"Unexpected character encountered while parsing value: e. Path '', line 0, position 0."}
I don't know why this comes. The JSON file is the following -> Click me I am the JSON link
Does anyone have any ideas?

Possibly you are not passing JSON to DeserializeObject.
It looks like from File.WriteAllText(tmpfile,... that type of tmpfile is string that contain path to a file. JsonConvert.DeserializeObject takes JSON value, not file path - so it fails trying to convert something like #"c:\temp\fooo" - which is clearly not JSON.

I solved the problem with these online tools:
To check if the Json structure is OKAY: http://jsonlint.com/
To generate my Object class from my Json structure: https://www.jsonutils.com/
The simple code:
RootObject rootObj= JsonConvert.DeserializeObject<RootObject>(File.ReadAllText(pathFile));

In my case, the file containing JSON string had BOM. Once I removed BOM the problem was solved.

I experienced the same error in my Xamarin.Android solution.
I verified that my JSON was correct, and noticed that the error only appeared when I ran the app as a Release build.
It turned out that the Linker was removing a library from Newtonsoft.JSON, causing the JSON to be parsed incorrectly.
I fixed the error by adding Newtonsoft.Json to the Ignore assemblies setting in the Android Build Configuration (screen shot below)
JSON Parsing Code
static readonly JsonSerializer _serializer = new JsonSerializer();
static readonly HttpClient _client = new HttpClient();
static async Task<T> GetDataObjectFromAPI<T>(string apiUrl)
{
using (var stream = await _client.GetStreamAsync(apiUrl).ConfigureAwait(false))
using (var reader = new StreamReader(stream))
using (var json = new JsonTextReader(reader))
{
if (json == null)
return default(T);
return _serializer.Deserialize<T>(json);
}
}
Visual Studio Mac Screenshot
Visual Studio Screenshot

I have also encountered this error for a Web API (.Net Core 3.0) action that was binding to a string instead to an object or a JObject. The JSON was correct, but the binder tried to get a string from the JSON structure and failed.
So, instead of:
[HttpPost("[action]")]
public object Search([FromBody] string data)
I had to use the more specific:
[HttpPost("[action]")]
public object Search([FromBody] JObject data)

This issue is related to Byte Order Mark in the JSON file. JSON file is not encoded as UTF8 encoding data when saved. Using File.ReadAllText(pathFile) fix this issue.
When we are operating on Byte data and converting that to string and then passing to JsonConvert.DeserializeObject, we can use UTF32 encoding to get the string.
byte[] docBytes = File.ReadAllBytes(filePath);
string jsonString = Encoding.UTF32.GetString(docBytes);

I had the same problem with webapi in ASP.NET core, in my case it was because my application needs authentication, then it assigns the annotation [AllowAnonymous] and it worked.
[AllowAnonymous]
public async Task <IList <IServic >> GetServices () {
        
}

I ran into this issue and it ended up being because of BOM characters in my input string.
Here's what I ended up doing:
String.Trim(new char[] { '\uFEFF', '\u200B' });
This resolved the issue for me.

In my case, I was getting an error on JsonConvert.PopulateObject().
My request was returning JSON that was wrapped in an extra pair of '[ ]' brackets, making my result an array of one object rather than just an object. Here's what I did to get inside these brackets (only for that type of model):
T jsonResponse = new T();
var settings = new JsonSerializerSettings
{
DateParseHandling = DateParseHandling.DateTimeOffset,
NullValueHandling = NullValueHandling.Ignore,
};
var jRslt = response.Content.ReadAsStringAsync().Result;
if (jsonResponse.GetType() == typeof(myProject.Models.MyModel))
{
var dobj = JsonConvert.DeserializeObject<MyModel[]>(jRslt);
var y = dobj.First();
var szObj = JsonConvert.SerializeObject(y);
JsonConvert.PopulateObject(szObj, jsonResponse, settings);
}
else
{
JsonConvert.PopulateObject(jRslt, jsonResponse);
}

If you are using downloading data using url...may need to use
var result = client.DownloadData(url);

In my scenario I had a slightly different message, where the line and position were not zero.
E. Path 'job[0].name', line 1, position 12.
This was the top Google answer for the message I quoted.
This came about because I had called a program from the Windows command line, passing JSON as a parameter.
When I reviewed the args in my program, all the double quotes got stripped.
You have to reconstitute them.
I posted a solution here. Though it could probably be enhanced with a Regex.

I had a similar error and thought I'd answer in case anyone was having something similar. I was looping over a directory of json files and deserializing them but was getting this same error.
The problem was that it was trying to grab hidden files as well. Make sure the file you're passing in is a .json file. I'm guessing it'll handle text as well. Hope this helps.

I had simular problem. In my case the problem was in DateTime format. It was just numbers and it is also know as EpochFormat or UnixTimestamp.
A part from my JSON:
"direction": "outbound",
"date_archive": 1554691800224,
"date_doc": 1524700800000,
"date_sent": 1524704189000,
"date_received": 1524704189000,
"date_store_till": 1712544600224,
So I've used an attribute like this:
[JsonProperty("date_received")]
[JsonConverter(typeof(MicrosecondEpochConverter))]
public DateTime? DateReceived { get; set; }
You can find MicrosecondEpochConverter code here: https://stackoverflow.com/a/19972214/4324624

I faced similar error message in Xamarin forms when sending request to webApi to get a Token,
Make sure all keys (key : value) (ex.'username', 'password', 'grant_type') in the Json file are exactly what the webApi expecting, otherwise it fires this exception.
Unhandled Exception: Newtonsoft.Json.JsonReaderException: Unexpected character encountered while parsing value: <. Path '', line 0, position 0

Please check the model you shared between client and server is same. sometimes you get this error when you not updated the Api version and it returns a updated model, but you still have an old one. Sometimes you get what you serialize/deserialize is not a valid JSON.

In my case, it was the lack of a default parameterless constructor !!!

In my case, I was calling the async service method without using await, so before Task is completed I was trying to return the result!

Suppose this is your json
{
"date":"11/05/2016",
"venue": "{\"ID\":12,\"CITY\":Delhi}"
}
if you again want deserialize venue, modify json as below
{
"date":"11/05/2016",
"venue": "{\"ID\":\"12\",\"CITY\":\"Delhi\"}"
}
then try to deserialize to respective class by taking the value of venue

This error occurs when we parse json content to model object. Json content type is string.
For example:
https://dotnetfiddle.net/uFClKj
Some times, an api that we call may return an error. If we do not check the response status, but proceed to parse the response to model, this issue will occur.

When I encountered a similar problem, I fixed it by substituting &mode=xml for &mode=json in the request.

Parse Json Object

I have an List error Entity which I used to pass errorId and error message to the UI layer.
public class ErrorEntity
{
public int ErrorId
{
get;
set;
}
public string ErrorMessage
{
get;
set;
}
}
}
I send the object to the Javascript I am serializing it to JSON.
The Json I am getting after serialization look like
[{"ErrorId":1,"ErrorMessage":"Test has not been prepared for tag EP105"},{"ErrorId":2,"ErrorMessage":"Test has not been prepared for tag EP105"}]
Now I need to parse this Json string to show the error message to the user. Please let me know how can I parse it. Do I need to write a for loop to traverse with in it.
EDIT In my master page I am trying to parse it.
function ShowErrorMsg(jsonObject) {
for (i = 0; i < jsonObject.Object.length; i++) { //Object is undefined here.
alert(jsonObject.Object.ErrorMessage);
}
}

Prefer JSON.parse() if it's available:
var jsonArray = JSON.parse(serializedString);
window.alert(jsonArray[0].ErrorMessage);
Fall back to eval() otherwise:
var jsonArray = eval(serializedString);
window.alert(jsonArray[0].ErrorMessage);

Try Json.NET

There is support in most browsers for parsing json, I recommend to use jQuery for this - you also can take a look at this
Be aware - Its better to use a library - and not using JS for this (JS is from the devil ;) )