Quickbooks File Repair — Error code: C=79

QuickBooks error C=79 reports errors in your inventory data -- the item records, quantities, and valuation links that QuickBooks tracks have become inconsistent. It is a recoverable condition in most cases, but inventory damage can ripple into reports and balances if left alone, so it is worth resolving promptly.

What C=79 means

QuickBooks ties every inventory item to a web of related records: quantities on hand, average cost, the transactions that move stock, and the accounts they post to. When one of those links breaks -- a quantity that no longer matches its transaction history, or an item record QuickBooks cannot reconcile -- it raises C=79 to flag inventory-data errors. The damage is usually confined to the inventory subsystem rather than the whole file.

Symptoms you'll typically see

• Inventory valuation or stock-status reports show negative or impossible quantities.
• Item counts disagree between reports.
• The error appears when saving an item-based transaction or running an inventory report.
• Average cost looks wrong for items you have not changed.

Common causes

• Interrupted writes during an inventory adjustment or item-receipt save.
• Network drops in multi-user mode while stock movements were posting.
• Damaged item or transaction links after a crash or power loss.

What you can safely try first

• Work on a copy of the file and keep the original untouched.
• Run File > Utilities > Verify Data, then Rebuild Data if Verify reports inventory problems.
• Review item quantities and adjust any that read as negative, since those often trigger the underlying inconsistency.
• If you have a clean .QBB backup from before the error, restoring it can be the quickest route back to consistent inventory.

When professional recovery is the safer path

If Rebuild does not clear C=79, or your inventory valuation still will not reconcile, the item-to-transaction links need record-level repair that the built-in utilities cannot perform safely. Our engineers rebuild the inventory structures, reconcile the quantity and cost links, and return a verified working file -- all done in-house in North America. We back it with a no-data, no-charge guarantee, so there is no fee if we cannot recover your data. See how QuickBooks data recovery works, or start a recovery.