Error calling provider on button click (FORM SAVED) - flutter

Question

I am posting a map on button click using provider, which calls Chopper service to post a map data to the server. It gives an error to the server which is something like this.
I/flutter ( 4801): Observatory listening on ************************************
E/flutter ( 4801): [ERROR:flutter/lib/ui/ui_dart_state.cc(199)] Unhandled Exception: Converting object to an encodable object failed: Instance of 'DateTime'
E/flutter ( 4801): #0 _JsonStringifier.writeObject (dart:convert/json.dart:688:7)
E/flutter ( 4801): #1 _JsonStringifier.writeMap (dart:convert/json.dart:769:7)
E/flutter ( 4801): #2 _JsonStringifier.writeJsonValue (dart:convert/json.dart:724:21)
E/flutter ( 4801): #3 _JsonStringifier.writeObject (dart:convert/json.dart:679:9)
E/flutter ( 4801): #4 _JsonStringStringifier.printOn (dart:convert/json.dart:877:17)
E/flutter ( 4801): #5 _JsonStringStringifier.stringify (dart:convert/json.dart:862:5)
E/flutter ( 4801): #6 JsonEncoder.convert (dart:convert/json.dart:262:30)
E/flutter ( 4801): #7 JsonCodec.encode (dart:convert/json.dart:172:45)
E/flutter ( 4801): #8 JsonConverter.encodeJson
E/flutter ( 4801): #9 JsonConverter.convertRequest
E/flutter ( 4801): #10 ChopperClient._encodeRequest
E/flutter ( 4801): #11 ChopperClient._handleRequestConverter
E/flutter ( 4801): #12 ChopperClient.send
E/flutter ( 4801): #13 _$PersonalPostingService.postPersonal
E/flutter ( 4801): #14 _FormState.build.<anonymous closure>.<anonymous closure>
E/flutter ( 4801): #15 _FormState.build.<anonymous closure>.<anonymous closure>
E/flutter ( 4801): #33 PlatformDispatcher._dispatchPointerDataPacket (dart:ui/platform_dispatcher.dart:282:7)
E/flutter ( 4801): #34 _dispatchPointerDataPacket (dart:ui/hooks.dart:96:31)
E/flutter ( 4801):
Exited (1)
This is where I am calling the function the body is a MAP of string, dynamic
child: RaisedButton(
onPressed: () async {
final form = _formKey.currentState;
if (form!.validate()) {
form.save();
showNotification();
await Provider.of<PersonalPostingService>(
context,
listen: false)
.postPersonal(data);
}
},
child: Text('Save'))),
The GET requests are working fine and are easily being displayed in a listview but the POST function is not working, just for the reference below is the chopper service for POST
#Post(path: 'http://157.......:8040/personal')
Future<Response> postPersonal(
#Body() Map<String, dynamic> body,
);