At long last, in early 2020, MetaMask will no longer reload web pages when the selected network changes. This will be a breaking change for dapps that have yet to support EIP 1193-compatible providers. We expect this to enable UX improvements for all dapps that use MetaMask.

If you are a MetaMask user, you should not have to do anything. If, however, you interact with unmaintained legacy dapps, you will have to reload the dapp in the browser whenever you change networks in MetaMask. If you are a dapp developer, we encourage you to continue reading.

If you want to learn more about our reasoning for doing this, you can check out previous post on this topic, from 2018. Note that the example code in that article is outdated.

Summary

Inside MetaMask, the user can change the selected Ethereum network or change at any time. Currently, whenever the user changes the network, MetaMask asks the browser to reload the open pages of any connected dapps. In Q1 2020, MetaMask will no longer ask the browser to do this. Instead, the dapp will have to listen for events emitted from the MetaMask inpage provider at window.ethereum .

Who is affected? What should you do instead?

If your dapp does not handle the network changing at any time after initialization, this will be a breaking change. To handle this, you need to listen for one of the events specified by EIP 1193, and handle the network change:

// you should use chainId for network identity, and listen for

// 'chainChanged' ethereum.on('chainChanged', chainId => {

// handle the new network

}) // if you want to expose yourself to the problems associated

// with networkId, listen for 'networkChanged' instead ethereum.on('networkChanged', networkId => {

// handle the new network

}) // if you want to do as little as possible, these three lines

// will emulate existing behavior ethereum.on('chainChanged', () => {

document.location.reload()

})

To understand why you should only use chainId , check out this article by the inimitable Pedro Gomes. For the authoritative chainId and networkId list, check out chainId.network.

Why are we doing this?

Dapp developers have asked us to stop forcing reload for a very long time. By asking the browser to reload the page, we’re taking away the dapp’s power to manage its own UX. Worse, reloading the webpage is usually terrible UX. To get a complete account of our reasoning, check out Dan Finlay’s post on this from 2018 (but don’t follow any of the example code).

Conclusion