I have generated GSTR-1 (Json) file through GST Offline Tool for the m/o July-2017 on 03-09-2017 and the same has been filed/uploaded at Online GST Portal (https://return.gst.gov.in/returns/auth/gstr/offlineupload).
On 05-09-2017 I have downloaded one Error (Json) file having errors message (The GSTIN is invalid. Please enter a valid GSTIN.) for some invoices, but there is no facility in GST Offline Tool to edit/update the GSTN of supplier.
the Invoice which have errors are not available on Online GST Portal, so the same can not be edited /updated online also.
E MAILED TO : helpdesk @ gst.gov.in : Kindly provide updated GST OFFLINE TOOL with download the error invoices in excel to edit/update also as there may be huge data to edit.