System.ObjectDisposedException: 'Cannot access a disposed object. Object name: 'System.String'.'

Question

I have this code that should upload all Attachment sent by user:

private async Task<List<AttchmentsMetaData>> UploadAttachments(IEnumerable<IFormFile> Attachments, string TaskTitle)
{
    // 1. Configure storage location and path generation
     string uploadPath = Path.Combine(_hostingEnvironment.ContentRootPath, "attachments",$"{TaskTitle}" ); 
    
    List<AttchmentsMetaData> metaData = [];
    // 2. Process and store each uploaded file
    Directory.CreateDirectory(uploadPath);
    foreach (IFormFile attach in Attachments)
    {
        string uniqueFileName = attach.FileName;
        string fullPath = Path.Combine(uploadPath, uniqueFileName);

        using (FileStream stream =  new FileStream(fullPath, FileMode.Create))
        {
            await attach.CopyToAsync(stream);
        }
        metaData.Add( new AttchmentsMetaData {id = Guid.NewGuid().ToString(), OriginalFileName = attach.FileName, ContentType = attach.ContentType, FileSize = attach.Length });
    }
    return (metaData);
}

If Attachment has only one item it works, but if has more than one it fails in the second iteration giving the above error:

System.ObjectDisposedException: 'Cannot access a disposed object. Object name: 'System.String'.'

I tried to add manual dispose for the file stream.
I tried to call the function multiple times and passing just one item.

Edited :

This is more info The thread 0x3838 has exited with code 0 (0x0). Exception thrown: 'System.ObjectDisposedException' in System.Private.CoreLib.dll Exception thrown: 'System.ObjectDisposedException' in System.Private.CoreLib.dll An exception of type 'System.ObjectDisposedException' occurred in System.Private.CoreLib.dll but was not handled in user code Cannot access a disposed object.

Object name: 'System.String'. at Microsoft.AspNetCore.WebUtilities.FileBufferingReadStream.set_Position(Int64 value) at Microsoft.AspNetCore.Http.FormFile.OpenReadStream() at Microsoft.AspNetCore.Http.FormFile.CopyToAsync(Stream target, CancellationToken cancellationToken) at ticketing_system_Dev_Nxt_level.Services.TaskService.UploadAttachments(IEnumerable`1 Attachments, String TaskTitle) in D:\ASP.NET\ticketing-system-Dev-Nxt-level\Services\TaskService.cs:line 334

Answer 1

Ok one of my colleagues solved it for me by changing the code inside the using block

using (FileStream stream =  new FileStream(fullPath, FileMode.Create))
    {
        attach.CopyTo(stream);
        stream.Flush();
    }