"Specified signature is expired" 401 Error Return

401 errors are authentication errors and "Specified signature is expired" is an error that occurs when the generated HMAC Signature has expired.

Since HMAC signatures last max 5 minutes from creation, HMAC signatures must be newly generated for every Coupang API call.

[Guide to generate HMAC signature] provides examples to generate HMAC.

If there is no problem with the program, please check whether the expiration date (180 days) of the OpenAPI key has expired.