By default, spreadsheet software will open with certain settings. The UPC column in the Product CSV spreadsheet will always open with the general setting, which converts large numbers to scientific notation. UPCs will be converted because they are 12 digits long.
If you are not editing/adding UPCs in your Product CSV, you can delete the UPC column from your spreadsheet entirely. This will leave your UPCs intact after you have uploaded the file.
If you are editing UPCs in your spreadsheet, it's important to make sure that you convert the column to the number or the custom (zero) setting; otherwise, you could end up with scientific notation in the UPC. Here are some ways that you can format your Product CSV spreadsheet file in Excel to prevent this from happening:
If these options do not work for you or you have a zero at the front of your SKU, then you need to convert the UPC column into a text column.
The solution is to use the Data > Text to Columns option in Excel. This will allow you to export the UPC column as a text field. Here's how to do that:
1) Select the UPC column in the Excel File:
2) Select the "Delimited" option in Excel:
3) Click the "Comma" option:
4) Choose the "Text" Data Format:
5) After, hit the finish button, and then you should be able to see your UPCs in a text format: