Amazon error 90188

Error 90188 means the check digit of a product code does not agree with the rest of the code. The last digit of a UPC, an EAN, or an ISBN-10 is calculated from the digits in front of it. Amazon runs the same calculation on the code in your file, and a last digit that differs from the calculated result returns error 90188.

What the processing report tells you

The processing report gives five entries for each failed row: the record number, the SKU, the error code, the type, and a message. Record 1 is row 3 of your file, so the row for a record sits at the record number plus two. For error 90188, the message names the field that holds the code. It does not say which digit of the code is wrong. Any digit in the code can be the mistyped one, and the error is reported at the check digit because the check digit is the digit the calculation can test.

What this error means

A product code carries an arithmetic check inside itself. The digits in front of the last one determine what the last one has to be. Amazon recalculates that digit for the code in your file and compares the result with the digit your file carries. The length of the code comes first in the same check. A code with the wrong number of digits for its type fails before the check digit question is reached, and recalculation has nothing to work on.

Causes, in the order to check them

One digit of the code was typed wrong. The mistyped digit can sit anywhere in the code, and the error lands on the check digit even when an earlier digit was the one mistyped.
The code lost a digit or gained one while it was copied between systems, which changed the length of the code.
The digits belong to a different product, and the check fails because the code was never this product's code.

How to fix it yourself

Count the digits of the code and compare the count with the length of its type. A UPC carries 12 digits, an EAN carries 13, and an ISBN-10 carries 10.
Where the length is wrong, take the correct code from the product packaging or your product code records and enter it in place of the code in the file. Recalculation cannot repair a code of the wrong length.
Where the length is right, compare the code in the file with the code on the product, digit by digit, and correct any digit that differs from the product.
Where every digit matches the product except the last one, calculate the check digit again and set the last digit to the result. A UPC and an EAN use modulus 10. For a UPC, add the digits in the odd positions, multiply that sum by three, add the digits in the even positions, and the check digit is the amount that brings the total to the next multiple of ten. For an EAN, the digits in the even positions carry the multiplication by three instead. An ISBN-10 uses modulus 11, with the digits weighted from 10 down to 2 and the check digit bringing the total to a multiple of eleven.
Upload the file again.

When the file cannot fix it

A code with the wrong number of digits was never the code of this product, so there is no last digit to repair. The same holds when the digits belong to a different product and only the check happens to fail. In both cases the correct code comes from the product itself, from its packaging or your code records, and the file takes that code as a replacement. A submission can also carry errors that sit outside the file, such as error 5665 for a missing brand registration or error 8026 for a missing category permission. The diagnosis lists those separately, with the reason and the step to take in Seller Central.

Check your file

The free diagnosis reads your failed file and the processing report Amazon returned. It shows every error by SKU, states which errors we fix automatically, which ones need your answer, and which ones the file cannot fix. You see the full breakdown before you pay anything. You can start from the FixFlatFile home page.

Requirements differ by category, and Amazon decides whether a file is accepted.