Invalid argument(s): Illegal argument in isolate message : (object is a closure - Function 'createDataList':.)

compute can only take a top-level function, but not instance or static methods.

Top-level functions are functions declared not inside a class and not inside another function

List<DataModel> createDataList(String responFroJson) {
...
}

class SomeClass { ... }

should fix it.

https://docs.flutter.io/flutter/foundation/compute.html

R is the type of the value returned. The callback argument must be a top-level function, not a closure or an instance or static method of a class.

As per today (2020. Aug) the compute is working fine with static methods. For me, the issue was that I was trying to return a http.Response object from the compute() methods.

What I did is I've created a simplified version of this class, containing what I need:

class SimpleHttpResponse {
  String body;
  int statusCode;
  Map<String, String> headers;
}

Then I've updated the original method from this:

static Future<http.Response> _executePostRequest(EsBridge bridge) async {
    return await http.post(Settings.bridgeUrl, body: bridge.toEncryptedMessage());
}
 

to this:

static Future<SimpleHttpResponse> _executePostRequest(EsBridge bridge) async {
    http.Response result = await http.post(Settings.bridgeUrl, body: bridge.toEncryptedMessage());
    if (result == null) {
      return null;
    }

    SimpleHttpResponse shr = new SimpleHttpResponse();
    shr.body = result.body;
    shr.headers = result.headers;
    shr.statusCode = result.statusCode;

    return shr;
}

Worked like charm after this change. Hope this helps somebody ranning into similar problem.