QuickBooks/Callbacks/Integrator/Errors.php
static public function e0x80040400_foundanerror($requestID, $user, $action, $ident, $extra, &$err, $xml, $errnum, $errmsg, $config)
	{
		if ($action == QUICKBOOKS_QUERY_UNITOFMEASURESET)
		{
			// Some versions don't support this query, so ignore this error
			return true;
		}
		
		return false;
	}
static public function e0x80040400_foundanerror($requestID, $user, $action, $ident, $extra, &$err, $xml, $errnum, $errmsg, $config)
	{
		if ($action == QUICKBOOKS_QUERY_UNITOFMEASURESET)
		{
			// Some versions don't support this query, so ignore this error
			return true;
		}
		
		return false;
	}
This error occurs when we send a request to QuickBooks that has an error, or that QuickBooks doesn't understand (old version of QuickBooks)

@param string $requestID
@return boolean