3790977 - Moving Average Price Negative (M8783) During Invoice Posting Despite Price Change — Wrong Price Unit On Purchase Order — S/4HANA Cloud Public Edition

• Error occurs during supplier invoice posting for a material valuated with moving average price.
• System displays: “Moving average price for material would be negative” (Message no. M8783).
• Issue persists even after changing the material price via “Change Material Prices” and following guidance from note 3755199.

• Product: SAP S/4HANA Cloud Public Edition
• Fiori UI for Invoice Verification (Public Cloud)

1. Post a supplier invoice for a material managed with moving average price.
2. Change the material price using the “Change Material Prices” app.
3. Follow the guidance from KBA : 3755199 - Moving average price for material would be negative- Message no. M8783
4. Attempt to post the invoice again and the system raises M8783 (“Moving average price for material would be negative”).

• The purchase order price unit was set incorrectly, so the goods receipt was posted as if the “price for the whole lot” were the “price per unit.”
• Inventory was overvalued at goods receipt; when posting the (lower, correct) invoice, the variance would drive the moving average price below zero, which is blocked by message M8783.
• Manually raising the material price did not resolve the issue because the deficit is determined by posted documents and current stock coverage, so subsequent stock movements reintroduce the block.

1. Validate which value is incorrect by comparing the PO/GR value and the invoice price against the material’s realistic average value.
2. If the goods receipt value is too high due to a wrong price unit on the PO:
   • Reverse the goods receipt using the standard GR reversal.
   • Correct the purchase order net price and, crucially, the price unit to reflect the intended “price per” quantity.
   • Repost the goods receipt at the correct value.
   • Post the supplier invoice.
3. If the invoice price is incorrect:
   • Do not reverse the goods receipt.
   • Request a corrected invoice or a credit memo from the supplier and then post accordingly.
4. Apply the same check-and-correct approach to all affected materials and correct the upstream source of the incorrect price (for example, manual entry template, purchasing info record, or external price feed) to prevent recurrence.
5. Optionally monitor similar patterns using value-flow monitoring tools and avoid manual material price increases unless explicitly required as a documented last resort.

• refer to: Valuation with Moving Average Price
• refer to: Change Material Prices (F6489)
• refer to: Material Value Flow Monitor
• refer to: Knowledge Base Article 3755199 — Moving average price for material would be negative (M8783)

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