Zorro uses no fractional size, but the IB API still issues this message randomly. You can either ignore it or get the newest Zorro version, 2.56 beta, where this message is suppressed.

In 2.56 beta, message not appear in Zorro, but in IB Gateway is same: "Your API version does not support fractional size rules. Please upgrade to a minimum version 163"

Anyway, Ask/Bid prices for Forex like EUR/USD, is not downloaded.


I suppose this will help:

Hello,
Thank you for contacting Interactive Brokers.
Please consider upgrading your API to the latest version.
FX pairs will be getting new fractional size rules (AUD.USD was just the first), so in the near future many forex pairs would be inaccessible via API for clients using libraries without Decimal size support.
Regards,
Konstantin B.
IBKR Client Services - API


Thanks