Could not enqueue task UploadTask

[MartinSchultz]

Hey. I'm failing to properly set up an upload task. Due to my previous post I learned to put my photo I take from the iOS asset picker and store it locally in the documents directory, to have a non-changing place for the background uploader.

The task is to upload it to a presigned URL bucket on Amazon S3. I have that code working without the background uploader, as http.StreamedRequest with PUT as method. Works proper. Now I want to port that using the background uploader.

Here's quite plain simple upload task code:

final task = UploadTask(
        url: url,
        filename: fileName,
        directory: "./",
        httpRequestMethod: "put",
        baseDirectory: BaseDirectory.applicationDocuments,
        headers: {
          "Content-Type": "octet-stream",
          "Content-Disposition": 'attachment; filename="$fileName"; user=${UserManager.singleton.getUserToken()}; event=${event.eventId}; idhash=$dbIdHash',
          "Content-Encoding": "identity",
          'event': event.eventId,
          'file_extension': fileExtension,
          'create_time': createTime.toString(),
          'latitude': latitude.toString(),
          'longitude': longitude.toString(),
          'authorization': UserManager.singleton.getUserToken()
        },
        fields: {
          'filename': fileName,
          'user': UserManager.singleton.getUserToken(),
          'event': event.eventId,
          'idhash': dbIdHash,
        },
        fileField: 'myFile',
        updates: Updates.statusAndProgress // request status and progress updates
    );

    final TaskStatusUpdate result = await FileDownloader().upload(task,
        onProgress: (progress) => Log.info('Progress: ${progress * 100}%'),
        onStatus: (status) => Log.info('Status: $status'),
        onElapsedTime: (time) => Log.info('Time: $time'),
    );
    Log.info("Background Upload->result: ${result.status}");
    Log.info("Background Upload->exception: ${result.exception}");
    Log.info("Background Upload->responseBody: ${result.responseBody}");
    if (result.status == TaskStatus.failed) {
      FileDownloader().cancelTaskWithId(result.task.taskId);
    }

Here's my output:

Background Upload->uploadFile filename: 27f440039fee318ad8d0262a052075a4_exif.jpg
[log] Background Upload->uploadFile directory: /Users/martin/Library/Developer/CoreSimulator/Devices/40394A4F-1D64-4704-9F0B-A62E32514FA5/data/Containers/Data/Application/946D9300-FC20-42FD-B600-3A0E92376AC3/Documents/9e81a8f9d9856e32dcb055e57c1ebc6817d7700de696136ace0b670f4ce4945c
[log] Background Upload->uploadFile file.path: /Users/martin/Library/Developer/CoreSimulator/Devices/40394A4F-1D64-4704-9F0B-A62E32514FA5/data/Containers/Data/Application/946D9300-FC20-42FD-B600-3A0E92376AC3/Documents/9e81a8f9d9856e32dcb055e57c1ebc6817d7700de696136ace0b670f4ce4945c//27f440039fee318ad8d0262a052075a4_exif.jpg
[log] Background Upload->result: TaskStatus.failed
[log] Background Upload->exception: TaskException: Could not enqueue task UploadTask{taskId: 112135104, url: https://tlbm-eventsphotoapp.s3.eu-central-1.amazonaws.com/_photos/51c55d17544e09f283bd7ab8c054e078788cab75d6eb8d503190fcce39206805.jpg?Content-Type=image%2Fjpeg&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAQZXRSACEYJ5TRFV2%2F20231003%2Feu-central-1%2Fs3%2Faws4_request&X-Amz-Date=20231003T124255Z&X-Amz-Expires=3600&X-Amz-Signature=40dc3231fd8dd308fbde5d2634fe4077d027266114b4c219be8e71a80efbd795&X-Amz-SignedHeaders=host, filename: 27f440039fee318ad8d0262a052075a4_exif.jpg, headers: {Content-Type: octet-stream, Content-Disposition: attachment; filename="27f440039fee318ad8d0262a052075a4_exif.jpg"; user=ffe176b78747a6fe07b780c432d48204722e390a4ffa97426082fd20423a8318; event=2LDK6PHY; idhash=2d944f8fd6295670d7b16ab587fa76b3fc08bc197856ef8b138edf5c4b2b8a3b, Content-Encoding: identity, event: 2LDK6PHY, file_extension: jpg, create_time: 1693497015, latitude: 0.0, longitude: 0.0, authorization: ffe176b78747a6fe07b780c432d48204722e390a4ffa97426082fd20423a8318}, httpRequestMethod: PUT, post: null, directory: ./, baseDirectory: BaseDirectory.applicationDocuments, group: default, updates: Updates.statusAndProgress, requiresWiFi: false, retries: 0, retriesRemaining: 0, metaData: } and fileField myFile, mimeType image/jpeg and fields {filename: 27f440039fee318ad8d0262a052075a4_exif.jpg, user: ffe176b78747a6fe07b780c432d48204722e390a4ffa97426082fd20423a8318, event: 2LDK6PHY, idhash: 2d944f8fd6295670d7b16ab587fa76b3fc08bc197856ef8b138edf5c4b2b8a3b}
[log] Background Upload->responseBody: null

I always get an "Could not enqueue task UploadTask" without further information. Any idea what I'm doing wrong?

[781flyingdutchman]

Quick reaction:

• The directory cannot start with / or .. If you don't need a subdirectory (e.g. because you stored your file in the Documents directory) then just leave it out
• Use "PUT" instead of "put"
• Make sure url, headers and urlQueryParameters are all url-encoded

Also, you may find additional log entries that explain why enqueue fails in the Console.

Let me know if this works - if not, I'll dig a little deeper!

[781flyingdutchman]

Also, you should not have content-type, content-disposition and content-encoding in your headers: they are set by the downloader based on the various fields you provide and the fileField, so if you include them here that may conflict.

Please share the Console output as well, so we can understand why the task cannot be enqueued.

[MartinSchultz]

All of that helped + my own stupidity. I only checked inside Android Studio, but once I ran it on Xcode directly, it was obvious I had a mistake in my path, so it couldn't find the file. Strangely that didn't get shown in the log output in Android Studio. I also needed to set post: "binary" and remove the fields: { ... } to make it a binary upload. Beforehand with fields it was multi-part upload.

Worked out very well so far. Upload is way faster than my previous implementation. Next onto the Android side.

Thank you very much for this great plugin.

[781flyingdutchman]

Great! And yes, logs from the 'native' side of the downloader will show up in Console (iOS) and LogCat (Android), not in the regular Flutter log in Android Studio. Closing this for now, let me know if you run into issues with the Android side :)