Looking at the 6,1,5 core code ( public virtual IFileInfo MoveFile(IFileInfo file, IFolderInfo destinationFolder)
I think that the CONTENT of the file is not being read and is returning null - System.ArgumentNullException: Value cannot be null. Parameter name: content at DotNetNuke.Common.Requires.NotNull(String argName, Object argValue) at DotNetNuke.Services.FileSystem.StandardFolderProvider.AddFile
using (var fileContent = GetFileContent(file))
{
try
{
destinationFolderProvider.AddFile(destinationFolder, file.FileName, fileContent);
}
catch (Exception ex)
{
DnnLog.Error(ex);
throw new FolderProviderException(Localization.Localization.GetExceptionMessage("UnderlyingSystemError", "The underlying system threw an exception."), ex);
}
}
Either that or the error is being thrown inside the GetFileContent method and gets bubbled up
throw new FolderProviderException(Localization.Localization.GetExceptionMessage("UnderlyingSystemError", "The underlying system threw an exception"), ex);