It looks like you are using the free conversion app of Aspose.Finance? Please correct us if you are not using the app. Apparently, your input document is not a valid XBRL/iXBRL file format, so you are getting an error. If this is not the case, could you please provide more details and your sample (input) file to show the issue? You may zip the file prior to attaching it, we will check it soon and share our feedback.