AI is often helpful, if not 100% accurate. Here's its take on your query...
"Probably not—reloading the Express Invoice backup and then deleting the duplicates there is more likely to put you back to a known-good state, especially since NCH’s sync behavior depends on the item list already matching between the two programs. NCH also notes that if Express Invoice is trying to update an item that no longer exists in Inventoria, that often happens after an item was created locally or deleted since the last successful synchronization.
What likely happened
When you deleted all items in Express Invoice, you probably broke the item matching that the sync process expects. NCH’s help says item sync imports all items from Inventoria, but the quantity updates only work correctly when the item and location setup still matches between the two programs. If items were removed locally, the next sync may fail because Express Invoice is now looking for items that no longer line up with Inventoria’s records.
Best approach
The safer path is:
Restore the Express Invoice backup.
Confirm the Inventoria connection settings are still enabled and the authorization key matches exactly.
Run the synchronization again.
Remove duplicate items only after the item list has synced cleanly and you can see which records are the real ones.
That approach preserves the original item records and gives you a consistent base to clean up from, instead of trying to rebuild the link from a wiped-out list.
Why not keep deleting first
If you delete items in Express Invoice before the sync is healthy, you can create a mismatch where quantity updates fail because the item no longer exists locally or no longer matches Inventoria’s item list. NCH’s documentation specifically points to this kind of mismatch as a common cause of sync errors. So the “delete first, sync later” method is usually the riskier option.
Practical check
Before restoring, make sure these match in both programs:
Synchronization is enabled in Inventoria and Express Invoice.
The authorization/access key is identical and case-sensitive.
The location name in Express Invoice matches an Inventoria location.
The items still exist in Inventoria and were not deleted there accidentally.
If you want, I can help you work through the exact recovery steps in the safest order."\
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