diff --git a/example/integration_test/downloader_integration_test.dart b/example/integration_test/downloader_integration_test.dart
index 78de461..4539535 100644
--- a/example/integration_test/downloader_integration_test.dart
+++ b/example/integration_test/downloader_integration_test.dart
@@ -2443,6 +2443,7 @@ void main() {
         taskStatusUpdate = TaskStatusUpdate(task, TaskStatus.failed); // reset
         FileDownloader().registerCallbacks(
             taskStatusCallback: (update) => taskStatusUpdate = update);
+        await Future.delayed(const Duration(milliseconds: 500));
         await downloader.retrieveLocallyStoredData(); // triggers status update
         await Future.delayed(const Duration(milliseconds: 500));
         expect(taskStatusUpdate.status, equals(TaskStatus.complete));
@@ -2478,6 +2479,7 @@ void main() {
         taskStatusUpdate = TaskStatusUpdate(task, TaskStatus.canceled); // reset
         FileDownloader().registerCallbacks(
             taskStatusCallback: (update) => taskStatusUpdate = update);
+        await Future.delayed(const Duration(milliseconds: 500));
         await downloader.retrieveLocallyStoredData(); // triggers status update
         await Future.delayed(const Duration(milliseconds: 500));
         expect(taskStatusUpdate.status, equals(TaskStatus.failed));
diff --git a/ios/Classes/Helpers.swift b/ios/Classes/Helpers.swift
index 07490d6..10257f6 100644
--- a/ios/Classes/Helpers.swift
+++ b/ios/Classes/Helpers.swift
@@ -18,3 +18,16 @@ extension URL {
         }
     }
 }
+
+/// Converts the [map] to a [String:String] map with lowercased keys
+func lowerCasedStringStringMap(_ map: [AnyHashable: Any]?) -> [String: String]? {
+    if map == nil {return nil}
+    var result: [String: String] = [:]
+    for (key, value) in map! {
+        if let stringKey = key as? String, let stringValue = value as? String {
+            result[stringKey.lowercased()] = stringValue
+        }
+    }
+    return result
+}
+
diff --git a/ios/Classes/Task.swift b/ios/Classes/Task.swift
index 4ef88f9..0088f10 100644
--- a/ios/Classes/Task.swift
+++ b/ios/Classes/Task.swift
@@ -200,6 +200,28 @@ enum TaskStatus: Int, Codable {
 struct TaskStatusUpdate: Encodable {
     var task: Task
     var taskStatus: TaskStatus
+    var exception: TaskException?
+    var responseBody: String?
+    var responseStatusCode: Int?
+    var responseHeaders: [String: String]?
+    var mimeType: String?
+    var charSet: String?
+    
+    func argList() -> [Any?] {
+        let finalState = isFinalState(status: taskStatus)
+        return taskStatus == .failed
+        ? [taskStatus.rawValue,
+           exception?.type.rawValue,
+           exception?.description,
+           exception?.httpResponseCode,
+           responseBody]
+        : [taskStatus.rawValue,
+           finalState ? responseBody : nil,
+           finalState ? responseHeaders : nil,
+           (taskStatus == .complete || taskStatus == .notFound) ? responseStatusCode : nil,
+           finalState ? mimeType : nil,
+           finalState ? charSet : nil]
+    }
 }
 
 /** Holds data associated with a task progress update, for local storage */
@@ -216,7 +238,7 @@ struct ResumeData: Encodable {
 }
 
 /// The type of [TaskException]
-enum ExceptionType: String {
+enum ExceptionType: String, Encodable {
     case
     
     // General error
@@ -248,7 +270,7 @@ enum ExceptionType: String {
  * The [description] is typically taken from the platform-generated
  * error message, or from the plugin. The localization is undefined
  */
-struct TaskException {
+struct TaskException : Encodable {
     var type: ExceptionType
     var httpResponseCode: Int = -1
     var description: String
diff --git a/ios/Classes/TaskFunctions.swift b/ios/Classes/TaskFunctions.swift
index 97dbefc..7f9f586 100644
--- a/ios/Classes/TaskFunctions.swift
+++ b/ios/Classes/TaskFunctions.swift
@@ -364,12 +364,20 @@ func processStatusUpdate(task: Task, status: TaskStatus, taskException: TaskExce
         let finalTaskException = taskException == nil
             ? TaskException(type: .general, httpResponseCode: -1, description: "")
             : taskException
-        let arg: [Any?] = status == .failed
-            ? [status.rawValue, finalTaskException!.type.rawValue, finalTaskException!.description, finalTaskException!.httpResponseCode, responseBody] as [Any?]
-            : [status.rawValue, responseBody, responseHeaders, finalResponseStatusCode, mimeType, charSet] as [Any?]
+        let statusUpdate = isFinalState(status: status) 
+            ? TaskStatusUpdate(task: task,
+                               taskStatus: status,
+                               exception: status == .failed ? finalTaskException : nil,
+                               responseBody: responseBody,
+                               responseStatusCode: (status == .complete || status == .notFound) ? finalResponseStatusCode : nil,
+                               responseHeaders: lowerCasedStringStringMap(responseHeaders),
+                               mimeType: mimeType,
+                               charSet: charSet)
+            : TaskStatusUpdate(task: task, taskStatus: status)
+        let arg = statusUpdate.argList()
         if !postOnBackgroundChannel(method: "statusUpdate", task: task, arg: arg) {
             // store update locally as a merged task/status JSON string, without error info
-            guard let jsonData = try? JSONEncoder().encode(TaskStatusUpdate(task: task, taskStatus: status))
+            guard let jsonData = try? JSONEncoder().encode(statusUpdate)
             else {
                 os_log("Could not store status update locally", log: log, type: .debug)
                 return }