tl;dr — Arbitrum One is migrating to Nitro on August 31st! Prep and test your contracts now! Refer to the migration notes, and stay up to date via our Twitter and Discord.

One week ago we carried out our migration of the Arbitrum Rinkeby testnet to Nitro. Overall the process went very well and now we’re looking forward to the mainnet migration of Arbitrum One to Nitro. We’re excited to share that we’re targeting the migration to take place on August 31st — exactly a year after we first opened Arbitrum One up in public beta!

We chose this date to ensure our ecosystem continues to have time to prepare for the migration, and because we think it’ll be a nice milestone to rally around — a fun birthday present for us all.

Continuing to Prepare for Nitro

Nitro is a significant technical upgrade, bringing changes across the stack that dramatically improve the experience of building on Arbitrum. We originally detailed these in our Arbitrum Goerli Nitro release, but as a refresher, Nitro is bringing:

• Advanced Calldata Compression, which further drives down transaction costs on Arbitrum by reducing the amount of data posted to L1.

• Ethereum L1 Gas Compatibility, bringing pricing and accounting for EVM operations perfectly in line with Ethereum.

• **Additional L1 Interoperability, **including tighter synchronization with L1 Block numbers, and full support for all Ethereum L1 precompiles.

• **Safe Retryables, **eliminating the failure mode where a retryable ticket fails to get created.

• **Geth Tracing, **for even broader debugging support.

• And many, many more changes.

Developers, now is the time to ensure your contracts and front-ends are ready for the migration, preparing any necessary changes and testing as much as possible. We strongly recommend deploying on an Arbitrum testnet if you haven’t already done so, with Arbitrum Goerli as our recommended, long-term option.

As we work towards the migration we’ll continue to update our migration notes, which keep track of any new and breaking changes, as well as our developer documentation.

Next Steps Before Nitro on Mainnet

After the Rinkeby migration having gone smoothly, we’re feeling confident and ready to bring Arbitrum One to Nitro. Over the next few weeks in the lead-up to the migration we’ll continue to coordinate with infrastructure providers, dapps, and our community at large to make sure everyone is fully briefed on what’s coming status and communicating any additional plans and updates.

About a week before the mainnet migration, on August 24th, we are planning to carry out a shadow fork migration as a final dress rehearsal before the mainnet migration. Shadow forking allows us to run a parallel chain that copies the state of another chain and still receives incoming transactions from the main chain, in this case Arbitrum One. Carrying this out and then migrating the shadow fork to Nitro provides full testing coverage for what we’ll be carrying out on mainnet a week later. We’ll be reaching out to partner teams to take part in the shadow fork as we get closer to the date.

Celebrating One Year on Mainnet

As mentioned we’re targeting August 31st since it allows for our developer community to keep preparing for the migration, but also because it lines up nicely with the anniversary of Arbitrum One on mainnet.

We’ve got a few fun things in the works to help celebrate our anniversary and Nitro, and will continue to share more about our plans in the coming weeks.

With all that said, get ready for Nitro!

tl;dr — Arbitrum One is migrating to Nitro on August 31st! Prep and test your contracts now! Refer to the migration notes, and stay up to date via our Twitter and Discord.

One week ago we carried out our migration of the Arbitrum Rinkeby testnet to Nitro. Overall the process went very well and now we’re looking forward to the mainnet migration of Arbitrum One to Nitro. We’re excited to share that we’re targeting the migration to take place on August 31st — exactly a year after we first opened Arbitrum One up in public beta!

We chose this date to ensure our ecosystem continues to have time to prepare for the migration, and because we think it’ll be a nice milestone to rally around — a fun birthday present for us all.

Continuing to Prepare for Nitro

Nitro is a significant technical upgrade, bringing changes across the stack that dramatically improve the experience of building on Arbitrum. We originally detailed these in our Arbitrum Goerli Nitro release, but as a refresher, Nitro is bringing:

• Advanced Calldata Compression, which further drives down transaction costs on Arbitrum by reducing the amount of data posted to L1.

• Ethereum L1 Gas Compatibility, bringing pricing and accounting for EVM operations perfectly in line with Ethereum.

• **Additional L1 Interoperability, **including tighter synchronization with L1 Block numbers, and full support for all Ethereum L1 precompiles.

• **Safe Retryables, **eliminating the failure mode where a retryable ticket fails to get created.

• **Geth Tracing, **for even broader debugging support.

• And many, many more changes.

Developers, now is the time to ensure your contracts and front-ends are ready for the migration, preparing any necessary changes and testing as much as possible. We strongly recommend deploying on an Arbitrum testnet if you haven’t already done so, with Arbitrum Goerli as our recommended, long-term option.

As we work towards the migration we’ll continue to update our migration notes, which keep track of any new and breaking changes, as well as our developer documentation.

Next Steps Before Nitro on Mainnet

After the Rinkeby migration having gone smoothly, we’re feeling confident and ready to bring Arbitrum One to Nitro. Over the next few weeks in the lead-up to the migration we’ll continue to coordinate with infrastructure providers, dapps, and our community at large to make sure everyone is fully briefed on what’s coming status and communicating any additional plans and updates.

About a week before the mainnet migration, on August 24th, we are planning to carry out a shadow fork migration as a final dress rehearsal before the mainnet migration. Shadow forking allows us to run a parallel chain that copies the state of another chain and still receives incoming transactions from the main chain, in this case Arbitrum One. Carrying this out and then migrating the shadow fork to Nitro provides full testing coverage for what we’ll be carrying out on mainnet a week later. We’ll be reaching out to partner teams to take part in the shadow fork as we get closer to the date.

Celebrating One Year on Mainnet

As mentioned we’re targeting August 31st since it allows for our developer community to keep preparing for the migration, but also because it lines up nicely with the anniversary of Arbitrum One on mainnet.

We’ve got a few fun things in the works to help celebrate our anniversary and Nitro, and will continue to share more about our plans in the coming weeks.

With all that said, get ready for Nitro!