Common Errors in Walmart EDI Files and How to Fix Them

Walmart EDI errors can result in rejected shipments, chargebacks, and payment delays. Understanding common EDI errors and how to fix them is critical to maintaining Walmart compliance and avoiding costly penalties. This guide covers the most frequent Walmart EDI errors, their causes, and step-by-step solutions.

Understanding Walmart's EDI Error Workflow

When you send an EDI document to Walmart (850, 856, or 810), Walmart's system validates the file in two stages:

Category 1: EDI 997 Functional Acknowledgment Errors

If you receive a rejected EDI 997, it means Walmart's system could not read the EDI file due to syntax errors. These are fundamental EDI formatting issues that prevent Walmart from even validating the business data.

Error 1.1: ISA/GS Identifier Mismatch

Error Message: "Unable to locate partner with AS2 ID" or "Document does not match your organization's ISA/GS identifiers"

Cause: The ISA ID qualifier, ISA identifier, or GS code is incorrectly configured on your end. Walmart's system cannot identify your company because the EDI header identifiers don't match Walmart's records.

Example: Your EDI system sends ISA*ZZ*YOURCOMPANY, but Walmart expects ISA*ZZ*1234567890 (your assigned ISA ID).

How to Fix:

• Contact Walmart EDI Onboarding to confirm your assigned ISA ID qualifier, ISA identifier, and GS application sender code
• Update your EDI software configuration to use the correct identifiers
• Verify that both the sender and receiver identifiers match Walmart's requirements exactly (case-sensitive, no extra spaces)
• Resend the EDI file with corrected identifiers

Error 1.2: Character Length Violation

Error Message: "Violation of character length" or "Segment exceeds maximum length"

Cause: One or more EDI segments contain data that exceeds the maximum allowed character length for that segment. For example, the N1 segment allows a maximum of 60 characters for the company name, but your data contains 75 characters.

How to Fix:

• Review the rejected segment in the 997 error details
• Consult Walmart's EDI mapping guide for the maximum character length for that segment
• Truncate or abbreviate the data to fit within the allowed length
• Update your EDI system to validate character lengths before transmission

Error 1.3: Missing Mandatory Segment

Error Message: "Incomplete or missing data in mandatory segments" or "Required segment not found"

Cause: The EDI file is missing a required segment. For example, an 856 ASN must include BSN, HL, TD5, REF, N1, and MAN segments. If any of these are missing, the 997 will be rejected.

How to Fix:

• Review Walmart's EDI mapping guide for the transaction type (850, 856, 810)
• Identify which mandatory segments are missing
• Update your EDI generation system to include all required segments
• Test the EDI file against Walmart's validation rules before sending

Error 1.4: Invalid Data in Segment

Error Message: "Invalid data" or "Data element contains invalid characters"

Cause: A segment contains data that doesn't match the expected format. For example, a date field contains letters instead of numbers, or a numeric field contains special characters.

How to Fix:

• Review the segment with invalid data in the 997 error details
• Verify the data format requirements in Walmart's EDI mapping guide (date format: YYYYMMDD, numeric fields: no commas or dollar signs)
• Correct the data format in your source system
• Implement data validation rules in your EDI system to prevent invalid data from being transmitted

Category 2: EDI 824 Application Advice Errors (ASN)

If your EDI file passes the 997 but receives an 824 with "ERROR" or "WARN," it means Walmart's system found issues with the business data in your ASN (856). These errors must be corrected and the ASN retransmitted before the shipment arrives at the DC.

Error 2.1: Missing or Invalid UPC/EAN

Error Message: "The Walmart item file does not recognize the UPC/EAN" or "Missing or invalid UPC"

Cause: The UPC code in your ASN (LIN segment) doesn't match Walmart's item master file. This can happen if:

• The UPC was entered incorrectly (typo, copy/paste error)
• The UPC has not been set up in Walmart's item file
• The UPC format is incorrect (missing leading zeros, check digit error)

How to Fix:

• Verify the UPC code matches the original 850 PO (use PlainEDI's 850 to CSV converter to extract PO UPCs)
• Ensure the UPC is 12 digits for UPC-A or 13 digits for EAN-13
• Contact Walmart Item Setup team if the UPC is correct but not recognized in Walmart's system
• Correct the UPC in your ASN and retransmit before shipment arrival

Error 2.2: Invalid GLN (Global Location Number)

Error Message: "Invalid GLN" or "The ASN contains the incorrect destination GLN in the N1 segment"

Cause: The GLN (Global Location Number) in the N1 segment of your ASN doesn't match the GLN listed on the 850 PO for the destination DC. Each Walmart DC has a unique 13-digit GLN that must be used in the ASN.

Example: The 850 PO lists GLN 0078742000015 for Walmart DC 6023, but your ASN contains GLN 0078742000022 (a different DC).

How to Fix:

• Extract the destination GLN from the original 850 PO (N1*ST segment)
• Verify the GLN in your ASN (N1*ST segment) matches the PO exactly
• Maintain a reference table of Walmart DC GLNs to prevent future errors
• Correct the GLN in your ASN and retransmit

Error 2.3: Missing SSCC-18 Barcode (MAN*GM Segment)

Error Message: "Missing MAN*GM segment" or "SSCC-128 pallet label missing in data"

Cause: The MAN*GM segment, which contains the SSCC-18 barcode for pallet/carton identification, is missing or incorrectly formatted in the ASN. Walmart requires SSCC-18 barcodes for all shipments to support labelless receiving.

How to Fix:

• Generate SSCC-18 barcodes for all pallets and cartons before creating the ASN
• Include the MAN*GM segment in the HL (Hierarchical Level) structure for each pallet/carton
• Verify the SSCC-18 format: 18 digits (Extension + Company Prefix + Serial + Check Digit)
• Use PlainEDI's 856 to CSV converter to verify SSCC codes are included before sending

HL*3*2*P~
MAN*GM*00123456789012345678~

Example: Pack level (P) with SSCC-18: 00123456789012345678

Error 2.4: GTIN Character Length Error

Error Message: "The IN/UK must meet the minimum GTIN character requirement"

Cause: The GTIN (Global Trade Item Number) in your ASN does not meet the minimum character length. GTINs must be 12 digits (UPC-A), 13 digits (EAN-13), or 14 digits (GTIN-14).

How to Fix:

• Verify the GTIN length in your ASN (LIN segment)
• Add leading zeros if necessary to meet the minimum length (e.g., 12345678 → 000012345678 for UPC-A)
• Ensure the check digit is correct using a GTIN check digit calculator
• Correct the GTIN in your ASN and retransmit

Error 2.5: ASN Not Downloaded

Error Message: "ASN Not Downloaded" or "No valid ASN submitted for purchase order"

Cause: Walmart's system did not receive a valid ASN for the purchase order before the shipment arrived at the DC. This can happen if:

• The ASN was never sent
• The ASN was sent too late (after shipment arrival)
• The ASN was rejected due to 997 or 824 errors and never corrected

How to Fix:

• Send the ASN simultaneously with the departure of the outbound shipment from your facility (Walmart best practice)
• Monitor 997 and 824 responses daily to catch rejections before shipment arrival
• Set up automated alerts in your EDI system for failed ASN transmissions
• If the shipment has already left, expedite ASN transmission and correction to minimize chargebacks

Category 3: EDI 850 Purchase Order Errors

While Walmart sends the 850 PO to you, parsing errors can occur if you misinterpret the PO data. These errors don't trigger 997 or 824 rejections, but they lead to downstream problems in the ASN and invoice.

Error 3.1: Incorrect MABD (Must Arrive By Date)

Problem: Misreading the MABD date in the 850 PO (DTM*002 segment) leads to late shipments and OTIF penalties (3% COGS).

Example: DTM*002*20250127~ means January 27, 2025, not July 27, 2025 (date format is YYYYMMDD, not MMDDYYYY).

How to Fix:

• Use PlainEDI's 850 to CSV converter to extract MABD dates in a readable format
• Verify the date format is YYYYMMDD (year first, then month, then day)
• Set up automated calendar alerts for MABD deadlines in your order management system

Error 3.2: Missing Department Number

Problem: Failing to extract the department number from the 850 PO causes invoice rejection. Walmart requires the PO number, department number, and GLN on all invoices (810).

How to Fix:

• Extract the department number from the 850 PO (REF*DP segment or PO1 segment depending on Walmart's format)
• Include the department number in your 810 invoice (REF*DP segment)
• Verify the department number matches the PO before sending the invoice

Error 3.3: Incorrect Ship-To Location

Problem: Shipping to the wrong DC or store because the N1*ST (Ship To) segment was misread or the GLN was entered incorrectly.

How to Fix:

• Always verify the N1*ST segment in the 850 PO contains the correct GLN and address
• Cross-reference the GLN with Walmart's DC directory to confirm the destination
• Include the correct GLN in your 856 ASN (N1*ST segment) to match the PO

Category 4: EDI 810 Invoice Errors

Error 4.1: Price Mismatch with PO

Problem: The invoiced price in the 810 (IT1 segment) doesn't match the price in the 850 PO, causing invoice rejection.

How to Fix:

• Extract the unit price from the 850 PO (PO1 segment) before creating the invoice
• Verify the IT1 segment in your 810 invoice uses the exact price from the PO (no rounding or adjustments)
• If the price changed, contact Walmart's buyer to issue a revised PO before invoicing

Error 4.2: Missing GLN or Department Number

Problem: The 810 invoice is missing the GLN (N1 segment) or department number (REF*DP segment), causing invoice rejection.

How to Fix:

• Always include the PO number, department number, and GLN on all invoices (Walmart requirement)
• Extract these values from the original 850 PO and include them in the 810 invoice
• Use PlainEDI's 810 to CSV converter to verify invoice data before sending

Error 4.3: Quantity Mismatch with ASN

Problem: The invoiced quantity in the 810 doesn't match the shipped quantity in the 856 ASN, causing three-way match failure.

How to Fix:

• Ensure the invoice quantity (IT1 segment) matches the ASN quantity exactly
• If you shipped less than the PO quantity, invoice only for the shipped quantity
• Implement a three-way match system in your ERP to verify PO → ASN → Invoice consistency

Best Practices to Prevent Walmart EDI Errors

1. Review 997 and 824 Messages Daily

Set up automated monitoring for EDI 997 and 824 responses from Walmart. Review errors daily and correct them immediately before shipments arrive at Walmart DCs.

2. Validate EDI Files Before Sending

Use PlainEDI to convert your EDI files to CSV before sending to Walmart. This visual validation step catches errors that automated systems might miss:

• Validate 850 POs to extract MABD, department numbers, and GLNs
• Validate 856 ASNs to verify SSCC codes, UPCs, and GLNs before shipping
• Validate 810 Invoices to verify prices, quantities, and department numbers

3. Send ASN Simultaneously with Shipment Departure

Walmart recommends sending the 856 ASN at the same time the shipment leaves your facility. This ensures enough time for ASN data validation in Walmart's system before the shipment arrives.

4. Maintain Reference Tables

Keep up-to-date reference tables for:

• Walmart DC GLNs (13-digit location codes)
• UPC/GTIN mappings for all your products
• Department numbers for product categories
• ISA/GS identifiers for your company

5. Implement Three-Way Match System

Build automated validation in your ERP or EDI system to verify:

• PO (850) → ASN (856): Quantities, UPCs, ship-to location match
• ASN (856) → Invoice (810): Quantities, prices, PO references match
• Alert on mismatches before EDI transmission

6. Test EDI Files in Walmart's Test Environment

Before going live with EDI changes or new product setups, test your EDI files in Walmart's test environment to catch errors before they impact production shipments.

Error Resolution Workflow

When you receive an EDI error from Walmart, follow this workflow:

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