Alrighty-roo… I seem to have answered my own question. I added a debug statement to output the XML response from the USPS API in…
I placed the statement below right before the return at the end of the _getXmlQuotes() function…
echo '<pre>Response: '.htmlentities($responseBody, ENT_QUOTES).'</pre>';//debug
I then added an item to my shopping cart and requested a shipping quote. The debug statement output this…
<Description>RECTANGULAR is an invalid container type for a REGULAR package and ALL service.</Description>
So apparently Rectangular is no longer valid? In any event, I changed my container type in the admin to “variable”, removed the debug statement and now everything appears to be working. Phew!