FileUploaderChunkSize Property

Gets or sets the chunk size used in chunked uploading mode. The default is usually 28.6 MB (or 4MB for ASP.NET Classic before 4.5). The default and highest value is determined from Web.config. For ASP.NET Core and ASP.NET Classic 4.5+, it is determined only from system.webServer/requestLimits/maxAllowedContentLength property in Web.Config. For ASP.NET Classic before 4.5, it is determined additionally from system.web/httpRuntime/maxRequestLength property in Web.Config.

With chunked uploading mode, which is the default mode on modern browsers, file is split into chunks and chunks are uploaded one by one, and then chunks are reassembled back on the server. The reason for using chunked uploading when possible, is to overcome server's default request limitations. By using chunking, normally you don't need to change any settings to allow uploading of very large files out of the box. Currently all upload methods except Html4 uses chunked uploading (Html5 or Flash or Silverlight), this is because Html4 cannot split into chunks and can only send the whole file in a single request (multipart/form-data).

Information on various request size limits:

• IIS by default has 30000000 (28.6 MB) request size limit, controlled by system.webServer/requestLimits/maxAllowedContentLength property in Web.Config, in bytes, maximum value is 4294967295 (4 GB). However maximum value is 2147483647 (2 GB) when the application is running under the NET 4.5 Integrated Pipeline Application Pool. This setting effects FileUploader, as it is an IIS setting, FileUploader cannot automatically override it.
• ASP.NET Core by default has 30000000 (28.6 MB) request size limit, controlled by IHttpMaxRequestBodySizeFeature.MaxRequestBodySize property in code, in bytes, maximum value is unlimited if null. This setting does not effect FileUploader, i.e FileUploader can automatically override it.
• ASP.NET Classic by default has 4096 (4 MB) request size limit, controlled by system.web/httpRuntime/maxRequestLength property in Web.Config, in kilobytes, maximum value is 2097151 (2 GB). This setting effects FileUploader only if you are running under server runtime lower than ASP.NET Classic 4.5 version, i.e when FileUploader cannot automatically override it.