Upgrades to the Ethereum Network Could Break Existing Smart Contracts

This article from CertiK explains that the Istanbul Ethereum hard fork will change several EVM gas costs (notably increasing SLOAD from 200 to 800 gas), which can cause deployed smart contracts—especially those that read state from fallback functions limited to 2300 forwarded gas—to fail. It advises developers to avoid assuming constant gas costs, audit contracts for fallback/state-read usage, and contact CertiK for assessment and remediation; it also summarizes future forks (Istanbul v2/Berlin and Ethereum 2.0) and related considerations.