E-invoice IRN error 2150: troubleshooting duplicate document number and IRN generation

When an accounts team tries to upload an outward invoice from Tally Prime, Zoho Books, SAP, or an offline JSON file, the upload may fail with the message: 2150: Duplicate IRN. Attempting to register a document again which is already registered and IRN is generated. This error stalls dispatch and delays e-way bill creation.

Accountants often assume the portal failed and click upload again. Repeated clicks generate the same error because the central registry has already recorded the document. Understanding how the e-invoice portal checks document identity prevents messy books and duplicate tax liabilities.

Legal basis: Rule 48(4) and Rule 46(b)

Under Rule 48(4) of the CGST Rules, notified registered persons must prepare their invoices by reporting specified particulars in FORM GST INV-01 on the Common Goods and Services Tax Electronic Portal to obtain an Invoice Reference Number (IRN). Under Rule 48(5), any invoice issued without an IRN by a person covered under Rule 48(4) is treated as invalid in law.

The 64-character IRN is a mathematical SHA-256 hash generated from four data elements: supplier GSTIN, document type (INV, CRN, DBN), document number, and financial year. The IRP maintains a central registry across all six notified portals.

In addition, Rule 46(b) of the CGST Rules prescribes that an invoice number must be a consecutive serial number not exceeding 16 characters, containing alphabets, numerals, and special characters (hyphen - and slash / only), unique for a financial year. If you attempt to re-use an invoice number within the same financial year, the central registry identifies the hash match and blocks the upload.

Why ERP systems trigger error 2150

Error 2150 usually occurs because of network timeouts or system synchronization gaps rather than intentional duplicate billing. The primary causes include:

• Network timeout during API handshake: The ERP sends the invoice JSON to the IRP. The IRP validates the payload, generates the IRN, signs the QR code, and sends the response. If your local internet flickers or your ERP database times out before saving the response, the ERP treats the call as failed. When you click retry, the IRP flags it as duplicate.
• Simultaneous parallel requests: Automated batch jobs firing multiple threads for the same batch can submit the same document twice in milliseconds. The first thread registers the IRN; the second thread receives error 2150.
• Document number reset across branches: Two distinct billing desks or branches using the same GSTIN generate the same serial number (such as INV-001) for the same financial year. Because the hash uses supplier GSTIN and financial year, the second upload gets rejected.
• Prior cancellation on the portal: An operator cancelled the IRN on the portal within the 24-hour window, but the billing software was not updated. Trying to re-submit the same number triggers rejection.

Step-by-step resolution: how to fix error 2150

Follow these exact steps on the portal to resolve the error without creating accounting mismatches:

Step 1: Check if the IRN is already live

1. Visit the official e-invoice portal at einvoice1.gst.gov.in.
2. Navigate to Search → e-Invoice Status from the public menu or log in to your account.
3. Enter your GSTIN, Document Type (Tax Invoice), Document Number, and Financial Year.
4. Submit the captcha to view the record.

Step 2: Act based on the portal status

The search result will reveal one of two scenarios:

• Scenario A: Active IRN exists. The invoice was registered successfully during the previous attempt. Copy the 64-character IRN, Ack No, and Ack Date. In your ERP (Tally Prime, Zoho Books, or SAP), locate the option to update IRN details manually or fetch status. Enter these details to complete the transaction and print the QR code. Do not create a new invoice.
• Scenario B: IRN was cancelled earlier. If the status shows cancelled, the central registry will never allow this invoice number to be registered again. You must mark this voucher as cancelled in your accounting records and generate a fresh invoice with the next consecutive serial number under Rule 46(b).

Worked scenario: handling a timeout mismatch

Consider Apex Industrial Supplies (GSTIN 27AAACA1234A1Z1). On 14 October 2026, the accountant generates invoice number AIS/26-27/0412 for an outward supply of machinery parts to a registered buyer.

Instead of editing the invoice number to AIS/26-27/0412A or altering values, the accountant checks einvoice1.gst.gov.in. The active IRN details are retrieved and pasted into the ERP. The invoice prints with the valid signed QR code. Taxable value of ₹2,50,000 and output tax of ₹45,000 auto-populate into GSTR-1 correctly without creating duplicate entries.

Impact on GSTR-1, GSTR-2B, and reconciliation

Every active IRN generated on the IRP auto-populates into the supplier Form GSTR-1. If an accountant erroneously creates a second invoice in the ERP instead of retrieving the first IRN, the supplier runs the risk of double reporting outward liability in GSTR-1 or leaving an orphaned invoice on the IRP.

For the buyer, only valid invoices reported on the IRP flow through GSTR-1 into their GSTR-2B. When duplicate or incorrect invoice numbers are issued, the buyer faces mismatches during monthly reconciliation. See our guide on how to handle duplicate invoices in GSTR-2B reconciliation. For detailed steps on fixing cross-period and document errors, read our guide on common GSTR-2B reconciliation errors and fixes and review our monthly GSTR-2B reconciliation checklist to ensure your purchase ledger matches auto-populated entries before filing GSTR-3B.

Related guides

• E-invoice signature verification and digital signature error fix
• E-invoice error 2265: HSN code digit length mismatch and turnover rules
• B2C dynamic QR code compliance: threshold rules, exemption scope, and UPI payment reconciliation under GST
• E-invoice error 2278: duplicate IRN on cancelled document explained
• E-invoice error 2283: resolving recipient GSTIN inactive, cancelled, or suspended status
• E-invoice exempted goods turnover threshold: Rs 5 Crore rule, aggregate calculation, and RCM rules
• E-invoice for B2B credit note: IRN generation deadline and rules
• E-invoice cancellation 24 hours deadline portal: rules and credit note steps

Frequently asked questions

Last checked: 14 October 2026. Sources: CBIC CGST Rules Rule 48, CBIC CGST Rules Rule 46, NIC e-Invoice Portal Error Codes Master, NIC e-Invoice Portal FAQs.