Why Did Polygon Hard Fork Its Blockchain?

Ethereum sidechain, Polygon, completed a network hard fork on January 17th, 2023, effectively resulting in a new Polygon blockchain. The hard fork was to fix some serious issues with the old chain. Before we go into the main issues that Polygon tried to solve, we will explain what a hard fork is so you can better understand how the upgrade affects the Polygon blockchain.


What Is a Hard Fork?

A fork is a blockchain protocol change for a blockchain update or a change to its rules. Forks can also be seen in the creation of a new cryptocurrency based on an older cryptocurrency, with the ability to change and tweak how the blockchain works. Since cryptos are open-source, code can be copied, edited, or reused.

A hard fork is carried out as a permanent departure from the previous version of a blockchain, which means that nodes running the previous version will no longer be accepted by the new version. The old network’s nodes and miners will need to upgrade their systems to participate in the new chain.

For a hard fork to occur, users of the chain have to vote to choose between the current version and the upgrade to the network. Thus, the upgrade can only happen when a majority of the blockchain’s validators agree to it.

Why Did Polygon Hard Fork?

There are two main reasons behind the Polygon hard fork.

1. To Reduce the Amount of Time Required to Complete a Block

Shortening the amount of time required to mine a block is aimed at reducing the chances of reorganization (reorg).

A reorg is a situation where a block is removed from a blockchain due to the introduction of a longer chain. This is caused when two miners work on adding blocks of transactions with similar difficulty to the blockchain at the same time, diverging from the main version of the chain. The miner adding the next block is faced with choosing which side of the fork is correct. When one is chosen, the other is overwritten. The miner who mined the removed block won’t be rewarded for the block, which has a damaging effect on the blockchain.

The Polygon hard fork is expected to reduce the time required to complete a block transaction and validate successful transactions.

Reducing the sprint length (the number of blocks a validator can produce consecutively) means that they will be created for a shorter period. In the case of Polygon, reducing the sprint length from 64 blocks to 16 blocks implies that a block producer will spend approximately 32 seconds instead of 128 seconds, thereby reducing the chances of reorgs. Therefore, it will lower the chances of having secondary validators kick in to produce blocks.

Based on the above, we propose a decrease in the sprint length from 64 to 16 blocks. This means that a block producer produces blocks continuously for much lower time as compared with the current 128 sec. This will help a great deal in reducing the frequency and depth of reorgs. This doesn’t affect the total time/no of blocks a validator is producing over a span and hence there would be no change in the rewards overall.

2. To Slow the Steady Rise in Gas Prices

The upgrade will also reduce the gas spikes by changing the BaseFeeChangeDenominator from 8 to 16. Changing the value of the BaseFeeChangeDenominator to 16 is expected to smooth out the base fee’s change rate. This will reduce the rate of severe fluctuations during high-demand periods, making Polygon users’ experiences better.

How Decentralized Is Polygon Really?

Although the hard fork is lauded as an advancement that should improve Polygon’s efficiency, many have questioned how truly decentralized a decentralized finance system is because only 15 validators were involved in the decision-making process to upgrade the system. This action raised concerns about how decentralized DeFi is.

Regardless, Polygon’s hard fork should bring extra stability to the Ethereum sidechain while reducing gas fee spikes—a winning combination for Polygon users.