Use JsonReader.setLenient(true) to accept malformed JSON

To resolve the Use JsonReader.setLenient(true) to accept malformed JSON error in Flutter, you can use the setLenient(true) method of the JsonReader class. This method allows the JSON reader to accept malformed JSON. Here's an example of how you can use it:

import 'dart:convert';

void main() {
  String jsonString = '{"name":"John","age":30,}'; // Malformed JSON with an extra comma

  try {
    var json = jsonDecode(jsonString);
  } catch (e) {
    if (e is FormatException) {
      // Handle the exception
      print('Malformed JSON');
      var jsonReader = JsonReader(jsonString);
      var json =;

In the code above, we first attempt to decode the JSON using jsonDecode. If a FormatException is thrown, we catch it and handle it by creating a JsonReader instance and calling setLenient(true) on it. This allows the reader to accept the malformed JSON. Finally, we read the JSON again using the lenient reader.

Please note that using setLenient(true) should be done with caution, as it may lead to unexpected behavior if the JSON is severely malformed. It's generally recommended to fix the JSON at its source if possible.

I hope this helps!