The maximum size of attachment and import files that can be uploaded to the server can be configured with the settings:
"MaxFileUploadPackageSize" which sets the maximum size of files that can be uploaded. Below In the example below the max size is 2 Mb.
"MaxFileUploadPackages" which sets the maximum number of packages the file will be sent in. Below In the example below the value is 4.
With the configuration below, a 1 Mb file would be sent in two packages of 500 Kb each.
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If none of the settings exists in the web.config file, "MaxFileUploadPackageSize" defaults to 2147483647 and the size of packages defaults to 100000.