3135 ERROR Customs option detail a is an error returned by FedEx that needs thorough review and multiple tests to identify the root cause of the problem.
This is a generic error for invalid value, wrong and incorrect configuration, or missing information that is required by Customs. Common issues are due to Harmonized code or incorrect payment type for the return label to name a few.
You can follow the checklist to fix the error:
1. Make sure the billing account and the order have the required information as mentioned in the support article How to begin shipping international orders [Information]
3. Run a test order using the live account and the billing account used to get the error. In this type of testing, you can only make changes to the order.
4. If you need to make changes to the settings of the billing account, copy the account from the live to a TEST client so you can delete and update configuration, as many times as you can, till you figure out the cause of the error.
5. If you can’t figure it out and still getting the error message, create a billing account from scratch under the TEST client using the support articles How to add and set up a FedEx Freight Billing Account [Step-by-Step guide] and How to begin shipping international orders [Information] as your guide. Test the billing account.
6. If your test process with no error, then compare the settings of your billing account against the account under the live client and present your findings to the customer.
7. Escalate to the next level when step 6 fails.