This error occurs when DHL cannot generate a label because the postcode does not match the expected format for the destination country.
Error message
"420506: Invalid Postcode Format"
What this means
The postcode entered in the merchant or customer address does not match DHL's required format for the selected country.
How to fix it
Review the postcode in the merchant or customer address.
Remove any spaces or unsupported characters if needed.
Confirm the postcode format matches the destination country requirements.
Save the changes.
Regenerate the label.
If the issue continues
Contact support with the RMA ID and a screenshot of the error.