You may receive following error while creating listing on ebay if you do not have credit card on your ebay for automatic monthly billing - SETTING UP AN AUTOMATIC PAYMENT METHOD IN YOUR EBAY ACCOUNT
Error Code: 121
Long Message You will be unable to complete this request until payment is made or a credit card is put on file for automatic monthly billing.
When you create a seller account on eBay, you'll need to add a payment method to pay for any eBay selling fees or charges. You can choose PayPal, direct debit, or credit card as your payment method.
Setting up an automatic payment method
Here's how to set up or change your payment method:
Go to your Account in My eBay.
Look for Payment methods for seller fees and select Change automatic payment method.
Choose your preferred payment method.
If you choose to pay by PayPal, you'll be redirected to the PayPal site to complete the process. If you choose direct debit or credit card, you'll need to enter your bank or card details.
If you choose direct debit or credit card, you'll need to enter your bank or card details. We'll need to verify your card so if it's declined during verification, while making payment, or at some other time, you'll need to contact the issuer of your card.
You usually can't use a pre-paid credit card to verify your account.
References: eBay help article Setting up and changing your payment method