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Beginning in MetaMask 8.1, we are correcting the value that the MetaMask extension emits with the chainChanged event for some custom networks. This could cause issues for sites that are relying on the incorrect behavior.

As a dapp developer, you should do the following to handle this change:

  1. Always use the chainChanged event to detect network changes. The networkChanged event is deprecated.
  2. If you need to continue using the networkChanged event, ensure that your dapp expects it to emit with decimal string values. Previously, this event could have emitted with a hexadecimal string for some custom networks.


The MetaMask provider emits the chainChanged and networkChanged events when the user switches the network in MetaMask. Due to a bug, in cases where the user added a custom network and specified its chain ID, MetaMask emitted the specified chain ID with networkChanged, and a nonsense value with chainChanged. …

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On November 16, 2020, MetaMask will stop injecting window.web3, and make a limited number of breaking changes to our Ethereum Provider API. Please use this GitHub issue if you have any questions.

You can find everything you need to know about the deprecations and why they’re happening in our Ethereum Provider documentation. When you’ve determined whether the changes affect you or not, please consult the migration guide to learn how to manage the changes.

Regardless of when you are reading this, you can already migrate to the new API. …

Many thanks to the talented teams and individuals that participated in our Generalized MetaTransaction Contest. We are humbled by the enthusiasm of you and the Ethereum community! You are the reason why we wouldn’t want to be working with anything else.

The contest is now over, and we were surprised by the number of excellent submissions we received. To fully evaluate all entries, the judges have chosen to actually try out the submitted tools with their own smart contracts! We want to give special thanks to our thoughtful and thorough judges:


Erik Marks

Developer at MetaMask. Lagom in all things.

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