Not possible to upload large files in the List Objects data binding in the File Manager in Blazor?

[Daniel Jonsson]

On https://blazor.syncfusion.com/documentation/file-manager/data-binding  there are 2 different data bindings methods for the File Manager in Blazor.

If I'm doing the `List objects` approach, I'm unable to upload large files.

Here's a small example:

<SfFileManager
    TValue="FileManagerDirectoryContent">
    <FileManagerEvents
        TValue="FileManagerDirectoryContent"
        OnRead="OnRead"
        ItemsUploading="ItemsUploading"
        ItemsUploaded="ItemsUploaded"
        ...
        />
</SfFileManager>

@code {
    private async Task ItemsUploading(ItemsUploadEventArgs<FileManagerDirectoryContent> args)
    {
        ...
    }

    private async Task ItemsUploaded(ItemsUploadedEventArgs<FileManagerDirectoryContent> args)
    {
        ...
    }
}

If I set breakpoints in both methods and try to upload a large file (one that is a bit over 100 MB), then it enters the `ItemsUploading` method. But then nothing happens. It never gets to the `ItemsUploaded` method. It just gets stuck like this without showing any progress:

If I try the retry-button, the page crashes with this message at the bottom of the page:

And in the web browser's developer tools's console it prints:

[2025-05-02T13:50:44.430Z] Error: System.NullReferenceException: Object reference not set to an instance of an object.
   at Syncfusion.Blazor.FileManager.SfFileManager`1.PerformHTTPUpload(String path, List`1 files, String action)
   at Syncfusion.Blazor.FileManager.SfFileManager`1.RetryHandler()
   at Microsoft.AspNetCore.Components.ComponentBase.CallStateHasChangedOnAsyncCompletion(Task task)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

Is this a bug that you are able to reproduce? Or what can I do to be able to upload large files in the `List objects` approach?

[Prasanth Madhaiyan]

Hi Daniel Jonsson,

Greetings from Syncfusion support.

Based on the details you shared, we understand that your requirement is to upload large files using the Blazor FileManager component. To achieve this, you need to configure the settings mentioned in the documentation link below:

Https://blazor.syncfusion.com/documentation/file-manager/how-to/upload-large-files 

Additionally, we would like to inform you that chunk upload support is also available in the Blazor FileManager component. 

To learn more about this feature, please refer to the following link:

Https://blazor.syncfusion.com/documentation/file-manager/upload#chunk-upload 

Check out the attached sample and let us know if you need any further assistance.

Regards,

Prasanth Madhaiyan.

[Daniel Jonsson]

Hi,

I have tried that, e.g.:

<SfFileManager
    TValue="FileManagerDirectoryContent">
    <FileManagerEvents
        TValue="FileManagerDirectoryContent"
        OnRead="OnRead"
        ItemsUploading="ItemsUploading"
        ItemsUploaded="ItemsUploaded"
        ...
        />
    <FileManagerUploadSettings ChunkSize="5242880" MaxFileSize="737280000"></FileManagerUploadSettings>
</SfFileManager>

But it doesn't make any difference. The upload still gets stuck. I wonder if it's because I'm doing 'List objects'? In the examples on the two pages you sent, they are both using 'AjaxSettings'.

[Prasanth Madhaiyan]

Hi Daniel Jonsson,

Sorry for the inconvenience caused.

Based on the shared details, we would like to inform you that chunk upload is not applicable for flat data, as the flat data approach only provides an event handler for upload functionality. Chunk upload functionality is only supported when using the AjaxSettings.url approach.

However, when we prepared the sample using the Upload Large File documentation, we were able to successfully upload large files in the FileManager Flat Data sample.

For your reference, we have attached the sample, and a screenshot. 

Sample: Attached as a zip file.

Screenshot: 

Please check the attached resources and let us know if you need any further assistance.

Regards,

Prasanth Madhaiyan.

Attachment: FileManagerFlatDataSample_12837c79.zip

[Daniel Jonsson]

Thank you very much Prasanth,

I took a look at your sample project. It seems like the key is this part for progress to be displayed sooner:

            <FileManagerUploadSettings ChunkSize="5242880" MaxFileSize="737280000"></FileManagerUploadSettings>

Do you know why that is?

It still takes about 4 seconds for the upload to start though. But decreasing the ChunkSize doesn't seem to have any effect. Is there anything else to do for an upload to start immediately?

It displays this dialog:

And then it takes like 4 seconds for the upload to actually start:

[Prasanth Madhaiyan]

Hi Daniel Jonsson,

We have checked and considered the mentioned requirement for the Blazor FileManager component flat data sample, as a feature on our end. Usually, Syncfusion will plan and implement the features based on feature rank, customer requested count, and volume wish list. We will implement and include this feature in any one of our upcoming releases.

The status of this feature can be tracked through our feedback portal below.

https://www.syncfusion.com/feedback/67719/need-to-enhance-the-large-file-upload-functionality-in-the-blazor-filemanager

Additionally, as mentioned in the previous update from this thread, the chunk upload functionality is only supported when using the FileManagerAjaxSettings approach. 

Please review the shared details and let us know if you need any further assistance.

Regards,

Prasanth Madhaiyan.

[Daniel Jonsson]

Okay, that's strange. When I added

            <FileManagerUploadSettings ChunkSize="5242880" MaxFileSize="737280000"></FileManagerUploadSettings>

the upload started much quicker (although still with the ~4 seconds delay), even though I'm using "flat data". So I experienced a change, even though you say this setting only play a role in "AjaxSettings". So that seems very strange.

Thanks for creating the feature request! It would be great if the upload would start instantaneously, so the user doesn't need to wonder what's wrong.

[Prasanth Madhaiyan]

Hi Daniel Jonsson,

Thank you for the update. Please track the feature feedback portal for further updates.

Regards,

Prasanth Madhaiyan.