Mastering Blockchain Programming with Solidity

Upgrading the contract

In the previous section, we looked at the StableToken contract code, which is prone to integer overflow attacks. Once the bug is identified for a production contract, you can upgrade the implementation contract and deploy it to fix the issue. 

ZeppelinOS manages the upgrading of the contract logic and storage structure seamlessly. Let's now use the following steps to fix the integer overflow issue present in the StableToken contract:

1. Manage the version of the project so that it becomes easy to track the changes that were introduced and fixed in a specific version of the contract. For that, let's bump the project version:

$ npx zos bump v2

This command will bump the project version from v1 to v2 and update ...