There is an issue where API endpoints returning error responses when certain corporate actions are processed or a stock gets delisted, due to asset prices not being available. To address this, a minor breaking change will be introduced on September 9, 2021, where non-nullable fields in the API response will become nullable, and values excluding account positions in unpriceable assets will be used instead. The change will affect the Trading API and Broker API live environments initially, with Paper Trading and sandbox environments enabled shortly after. The update aims to keep the API available while mitigating potential errors.