If you're receiving this error while fetching rates or attempting to ship an order in SKULabs, this is a sign that your UPS account may be suspended. The most common cause of this issue is that your UPS credentials are incorrectly entered for your UPS account on SKULabs or EasyPost. Another potential cause is due to billing details being expired.
You may still be able to ship in other software like WorldShip while you encounter this type of issue, that is normal behavior for the types of anti-fraud / anti-abuse holds UPS can place on an account.
Follow these steps in order to restore access to your UPS account through SKULabs:
Disable the UPS account in your carrier account settings on SKULabs. Repeated attempts to use your UPS account will extend the lock out.
Verify your UPS credentials and billing details have not changed or expired, and update them in SKULabs if they have.
Contact UPS or call 1-800-742-5877 (1-800-PICK-UPS) to ask "what kind of hold has been placed on my account" because you're getting the error "The Shippers shipper number cannot be used for the shipment" while shipping using the UPS API.
If you still can't use your UPS account on SKULabs, wait the indicated amount of time or 24 hours for the hold to be released and try again.
We always recommend maintaining multiple carrier accounts on SKULabs enabling you to continue operations while one carrier is suffering an outage or your account otherwise can't be used to create labels temporarily as you might be experiencing now.
If you can't ship your orders using an alternate carrier, you may want to try UPS WorldShip. You can still create manual shipments in SKULabs with tracking numbers generated outside SKULabs so your seller statistics are unaffected and inventory is properly deducted.
Additional details from the UPS.com website:
We're sorry you're having trouble logging in. For security reasons you're locked out if you enter the wrong User ID and password combination 3 times within a 10 minute period. UPS representatives can't unlock the User ID. Please wait at least 30 minutes before trying to log in again, this includes if your password was just reset.
This article is valid for the following errors:
The UserId is currently locked out, please try again in 30 minutes.
The Shippers shipper number cannot be used for the shipment