Attachments are being uploaded to the server in packages to allow for attachments of any size to be uploaded with a reasonable user experience.
The packaging within uploads can be controlled with the settings:
"MaxFileUploadPackageSize" which sets the maximum size of each packet that a file is split into. In the example below the max size is 2 MB. If you upload a file that is bigger than the package size, the file is split into as many packages of the MaxFileUploadPackageSize as possible, and at last a smaller package with the remainder of the file.
"MaxFileUploadPackages" which sets the maximum number of packages the file will be sent in. In the example below the value is 4.
With the configuration below, a 5 MB file would be sent in two packages of 2 MB each and one package of 1 MB
The maximum upload file size is calculated as MaxFileUploadPackageSize * MaxFileUploadPackages.
If you send a file exceeding the size limit, you will get this error message (in the above case, but with MaxFileUploadPackages = 1) :
If you for some reason don't want the system to break an upload file into packages, just set MaxFileUploadPackages to 1 and MaxFileUploadPackageSize to the maximum file size you want to be able to handle. We don't recommend limiting MaxFileUploadPackages and/or using a large MaxFileUploadPackageSize as it may impact user experience during heavy uploads and possibly make the system more fragile to network issues.
If you start adding these configurations, please make sure that the rest of your http pipeline and network devices can handle large single requests.
If none of the settings exists in the web.config file, the maximum upload file size defaults to 2.147.483.647 B (2 GB) and the size of packages defaults to 100.000 B.