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# How to Troubleshoot Synchronization Errors with Supplier Files

When syncing product data from a supplier file, several issues can prevent stock, price, or product information from updating correctly. This guide summarizes common problems and the steps to resolve them.

## Check Product Identifier Mapping
* Ensure the column mapped as **Product Identifier** actually exists in your supplier file.
* If the mapped identifier (e.g., "item number") is not present in the file, no products can be matched or updated.
* Confirm with your supplier that the file you are connecting to is the correct one and includes a valid identifier (SKU, barcode, or another unique field).

## Verify Shopify Location Availability
* If stock is not updating, check whether the product is assigned to the **same location** you selected in Stock Sync.
* For example, if the feed is configured to update the **TKC** location, ensure the product is available at the TKC location in your Shopify store.
* Products not stocked at the selected location will not update.

## Validate File Structure (CSV, Sheets, etc.)
* Errors such as **"Incorrect row separator"** generally indicate formatting issues in the supplier file.
* Review the file in a plain-text editor and check for:
* Consistent line endings
* Proper delimiter usage (commas, semicolons, etc.)
* For Google Sheets feeds, verify that the preview sync shows updates. If preview works, the file format is usually acceptable.

## Confirm File Name and Availability
* For FTP/SFTP imports, verify that the file name and path match exactly what is on the server.
* Example: If the server lists the file as `/products_export_1.csv`, ensure the same is entered in Stock Sync.
* If the file is different from expected, confirm with your supplier.

## Test Preview Sync
* Use **Preview Sync** to identify whether Stock Sync can read the file and detect updates.
* If preview shows correct updates but sync fails, revisit field mapping, location settings, or file format.

## When to Contact the Supplier
You may need to reach out to your supplier for:
* Missing identifier columns
* Incorrect or empty export files
* Permission or access issues on FTP/SFTP servers
* Unexpected changes on their server or feed configuration that may cause sync failures

If issues persist after these checks, contact Stock Sync support with:
* Feed name
* Sample SKU or barcode not updating
* File source link or file copy
* Screenshot of your field mappings