Resolve Carrier API Rate Limit Errors
This article explains “Rate Limit Exceeded” (429) errors and how to upgrade your carrier API plan to ensure your shipping services continue without interruption.
What is happening?
One or more carrier API keys associated with Your merchant Company has exceeded carrier-imposed rate or transaction limits.
Carrier enforcement now requires affected API credentials to move from free or trial access to a paid API plan to support current request volumes. Common carriers enforce strict limits for free or entry-level API access. When these limits are exceeded, carriers return 429 errors.
Moving to paid API access supports production-level traffic and significantly reduces the risk of service interruption.
Impacted Carriers
U Carrier
U Carrier enforces request-based rate limits. Current U Carrier API access (often the default developer access) does not support the required request volume for Your merchant Company customer services.
Solution: U Carrier paid API access is required to maintain service delivery.
View Pricing and plan details →F Carrier
F Carrier enforces a daily transaction quota at the organization level. Once the quota is reached, requests return 429 errors until the next reset window (usually the next day).
Solution: F Carrier paid API access is required to maintain customer services without daily interruptions.
View Quotas & Rate Limits Guide →Action Required
To resolve these errors, please complete both steps below:
- Upgrade at the Carrier: Log in to your carrier account (U Carrier or F Carrier) via the links provided above and upgrade your API credentials to a production/paid plan that supports higher volumes.
- Update in your app Company settings: Once you have your new credentials, you must update them in our platform.
Navigate to your Settings > Carriers page to add or replace credentials for U Carrier, F Carrier, and any other active carriers.
Frequently Asked Questions
What occurs if no action is taken?
If the license is not upgraded, Carrier rate-limit or quota errors will continue. Services used by Your merchant Company (such as quoting, label generation, or tracking) may not function correctly for your customers.
Where can I obtain help?
Please contact our merchant support team for assistance with understanding carrier plan upgrades or how to update your credentials within our platform.