Missing delivery methods and CartValidationOutput in custom calculators
Key Takeaway
If delivery methods don't load at checkout and no error appears, first check whether the shipping calculator is custom. Custom extensions should create CartValidationOutput records when they fail.
Custom calculators and Commerce extensions let a B2B Commerce store run its own logic during checkout, for example to calculate shipping or prices. When a custom shipping calculator fails quietly, delivery methods can fail to load with no error shown, and checkout can get stuck. So custom code should report its failures as well as do its normal work.
How to troubleshoot missing delivery methods
When delivery methods don't load at checkout and no error appears, start with the shipping calculator:
- Find out whether the shipping calculator is a custom implementation.
- If it is custom, confirm that it successfully generates and returns delivery methods.
- Then confirm that it creates
CartValidationOutputrecords for failure scenarios, because without them checkout may get stuck in a bad state.
Because this symptom shows no error, what the calculator does when it fails matters as much as what it does when it succeeds. A custom shipping calculator that fails without creating CartValidationOutput records leaves checkout stuck instead of surfacing the problem.