- Failure | ErrorCode:21915259
<br />ShortMessage:Package type - FRE deprecated.
<br />LongMessage:Package type - Flat Rate Envelope is deprecated. Package Type is converted to Package/Thick Envelope.
As the error outlined, the particular Flat Rate Envelope package type is deprecated and the item would be listed with package type converted to Package/Thick Envelope. You can double check this eBay link and you would be able to see further details about the available and general package types, that can be used and also this one, as it goes into further detail and contains additional information for the package types, which are available for thr USPS and UPS domestic and international shipping services.