Peak billing hours toward the end of each month often lead to network timeouts, 504 gateway errors, and connection drops on the Invoice Registration Portal (IRP). When an ERP or billing software sends an invoice payload and loses connection before receiving the signed JSON and QR code, finance teams face an operational dilemma: did the portal generate the IRN, or did the request fail before reaching the database?
Understanding network errors and statutory validity under Rule 48
Under Rule 48(4) of the CGST Rules, notified taxpayers must prepare invoices by including particulars in FORM GST INV-01 after obtaining an IRN from the Common GST Electronic Portal. Additionally, Rule 48(5) of the CGST Rules clarifies that any invoice issued without an IRN by a covered supplier is not treated as a valid tax invoice.
Because goods cannot move without a valid document containing the IRN and QR code, dispatch teams often panic during network outages. A common impulse is to create a new invoice in the ERP (such as changing INV-101 to INV-101A) and generate an IRN for the new number. This creates duplicate billing and unneeded debit or credit notes, because the original request might have actually succeeded on the IRP server.
Common mistake: Creating a new invoice number after a network timeout causes duplicate sales entries in your books. Once an IRN is created, it cannot be modified or deleted, and cancellation is restricted after 24 hours.
Workaround protocol for handling portal network timeouts
When your accounting software logs a network timeout or connection reset during payload transmission, execute these sequential steps:
- Wait 60 to 90 seconds: Do not spam the endpoint with back-to-back POST calls. Allow the IRP queue to clear pending transactions.
- Query by document details (Get IRN by Doc Details): Call the portal inquiry API or log into the NIC e-Invoice portal. Navigate to Search → e-Invoice / IRN to check if an IRN was generated for your document number, financial year, and document type.
- Interpret error code 2150 on retry: If you resubmit the exact same payload with the identical invoice number and receive NIC e-Invoice error code 2150 (Duplicate IRN), the portal did receive your earlier submission. Error 2150 confirms the document is registered. You can retrieve the signed IRN using the document lookup function.
- Check master validation errors: If the connection drop occurred due to client-side payload rejection, verify that the master details are valid. For recipient validation issues, review how to resolve recipient GSTIN inactive errors before re-attempting transmission.
Worked example: handling a timed-out dispatch batch
A manufacturing unit in Pune issues commercial invoice INV-842 for taxable machinery parts valued at ₹2,50,000 to an Ahmedabad buyer during peak month-end traffic at 5:30 PM.
| Component | Taxable value | IGST rate | Tax amount | Total invoice value |
|---|---|---|---|---|
| INV-842 (Parts dispatch) | ₹2,50,000 | 18% | ₹45,000 | ₹2,95,000 |
The transmission process encounters a network timeout:
- At 17:30:15, the billing ERP posts the JSON payload to the IRP.
- At 17:30:45 (after 30 seconds), the connection drops with an HTTP 504 Gateway Timeout without an IRN response.
- The dispatch team holds vehicle departure instead of generating INV-842A.
- At 17:32:00, the automated retry job submits the identical payload for INV-842.
- The portal returns response code 2150: "Duplicate IRN: attempting to register a document again which is already registered and IRN is generated".
- The ERP uses the Get IRN by Document Details API, pulls the existing 64-character hash and signed QR code generated at 17:30:28, and prints the invoice.
By relying on retry logic and error 2150 detection, the company avoided generating ₹2,95,000 in duplicate outward liability.
Impact on GSTR-1 and auto-population
As documented in the GSTN GSTR-1 user guide, data from generated e-invoices auto-populates from the IRP into tables 4A, 4B, 4C, 6B, and 6C for B2B supplies. If network timeouts cause an operator to raise duplicate invoices for a single transaction, both entries appear in Table 4A of GSTR-1, inflating output tax liability on the GST portal.
“Once an IRN is generated for an invoice it cannot be modified or deleted.” NIC e-Invoice System FAQ
Following a disciplined retry workflow safeguards return auto-population and avoids the need for manual record deletions in GSTR-1 before filing.
Frequently asked questions
What should you do when an e-invoice generation request times out without a response?
Never generate a fresh invoice number immediately. Query the portal using the document details or check whether error code 2150 is returned on retry, confirming that the earlier payload was processed.
How does error 2150 help in resolving network timeouts?
Error code 2150 indicates duplicate IRN. When received after a network timeout, it confirms the original invoice was registered by the portal, allowing you to fetch the existing IRN without issuing duplicate billing.
Verify inward e-invoices in your GSTR-2B
When suppliers face portal network delays, their e-invoices may auto-populate into your return on different dates. Upload your GSTR-2B and purchase register into our browser reconciliation tool to instantly track missing supplier documents. Your GSTR-2B and purchase register files are read in your browser and never uploaded to any server.
Last checked: 22 October 2026. Sources: CBIC CGST Rule 48, NIC e-Invoice Portal FAQ, GSTN GSTR-1 Guide.