Why Shibuya using the wrong chainID so many years?

I posted this topic in discord ( Japan channel ).
And now asking core team about it through an agent.
Waiting for answer.

I think it should be shared with non-Japanese people as well.

Astar testnet, Shibuya using wrong chainID( 81 ) long time( from start ).
It belong to Japan Open Chain Mainnet, officially.

Many developper know about it, but they don’t point it out or improve it. I don’t know why?

Considering the future multi-chain era, I don’t think this will continue as it is.

JOC( Japan Open Chain ) has recently become more active.
And many web3 & data tools don’t work well from this( wrong chainID ).

:sparkles: We can’t choose Shibuya, Shibuya doesn’t officially exist. :sparkles: :sob:

For example I use LayerZeroScan ( https://layerzeroscan.com/ ) to check the status of the bridge problem, JOC Mainnet & Astar testnet are same chainID, so it don’t work well.

In a simpler case, user can’t use Metamask, JOC & Shibuya chain at the same time ( or can’t use unofficial Shibuya chain in the future ).

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A better question would be, why did JOC choose for a ChainID that already exist. They are making it very difficult now for them and their users.

When we registered Shibuya, ChainID 81 was free. Can you explain more, why this was wrong at that time to take 81?


The registration of a chain ID for EVM is actually is FCFS, the later team should be doing research before registering a chain ID. This kind of issue actually already being discussed years ago before the rising of EVM-based chain. And I agree with Maarten, that when Astar registered ID 81 is free, and no one is using it, and our Shibuya testnet was already existed from 3 years ago.


I don’t know why?

But I think ChainID 81 is NOT belong to Astar( Plasm ) officially, Even if Shibuya was already existed from 3 years ago. I think.
( At least this two years long, officially, I know. Before that, I dont know. )

I’m just wondering, and I just want this problem to be resolved as a user.

:snowflake: DONT ask me ( Shiden = naoyo4 ) again !! :snowflake: , Ask JOC or FCFS etc, please!! :smiling_face_with_three_hearts:

:snowflake: And answer it and solve it !! :snowflake:

AND DONT BAN US ANY MORE !! ( We need more accounts ?? on discord or telegram or forum ?? ) without any reason. Please!! :smiling_face_with_three_hearts:

Ask again, where is Shibuya officially exist ?

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Shibuya First Block was generated 3 years ago: 2021-09-06 14:14:00 (+UTC)

Chain ID 81 was registered for Shibuya on 2021-09-06.


So, what ?
Ask again, where is Shibuya officially exist ?

To be exact, this ethereum repo GitHub - ethereum-lists/chains: provides metadata for chains is where projects can register IDs.

However, there is no central authority that controls chain IDs, anyone can use any number and the social consensus of first come, first served applies.

In the case of JOP, they are taking a huge risk by using the existing Shibuya ID, as three years of transactions on Shibuya can now be replayed on the JOC chain, and they are therefore facing the risk of replay attacks on their chain.

Note: there are 6 million blocks on Shibuya, many of which contain EVM transactions that can be replayed.

Shibuya ID 81 was not registered on Chain at the time, as this is not a mandatory practice and was not common for testnet networks. However, mentions of Shibuya ID 81 on the internet were present since September 2021 and also in 2022.

The debate is not about who owns chain ID 81 at the moment, but about the big risk to JOC of using an existing chain ID and therefore the risk for their ecosystem and users.


Hi @Gaius_sama @Maarten @souleater,

Thank you for the very informative advice.

I thought it was a very important point. Regarding the topic of ID81, I have connections with the JOC, so I would like to share information with the relevant parties at JOC.

I look forward to your continued support.


@tksarah Thank you for your contribution. Any progress ? :pray:

This issue sharing has already taken place and is currently being confirmed by the JOC.

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Below is from JOC to me. I belong both community. :four_leaf_clover:
Original Japanese and translate to English by GPT-4o.


チェーン81はAstar様含め、世界では過去には様々なテストチェーンが81番を利用した実績がございますが、最終的にはEthereum Foundationにて弊社のJapan Open Chainがメインネットとして正式認定されております。Ethereum Foundationが認定し管理するチェーンIDが事実上のデファクトとなっており、他のウォレットがそちらを正式なものとして採用することが一般的であるため、大変恐縮ですが他のテストチェーンを新しいIDで立て直していただくことが必要であると思われます。なお、Japan Open Chainのテストネットも、当初99999番で立てていたところ、すでにそのチェーンがEthereum Foundationに他のテストチェーンとして登録されていることが判明し、10081番のチェーンを立て直した実績もございます。その後10081番のテストチェーンとして、Ethereum Foundationに登録しております。

今後ともJapan Open Chainをよろしくお願いいたします。

Thank you for your continued support. I am writing to follow up on the matter we discussed previously.

Regarding Chain 81, various test chains have historically used the number 81 globally, including those of Astar. However, our Japan Open Chain has been officially recognized as the mainnet by the Ethereum Foundation. The chain ID managed and certified by the Ethereum Foundation has effectively become the de facto standard. As a result, other wallets generally adopt this as the official chain ID. Therefore, we regret to inform you that it is necessary to re-establish other test chains with a new ID.

Additionally, our Japan Open Chain testnet was initially set up with the ID 99999, but we discovered that this chain ID was already registered by the Ethereum Foundation for another test chain. Consequently, we re-established it with the chain ID 10081. This test chain with ID 10081 is also registered with the Ethereum Foundation.

We appreciate your continued support of Japan Open Chain.

@Gaius_sama @Maarten

As posted in the forum by “Naoyo4,” the response I received from the JOC side was the same.
I am translating from the Japanese version I received:

“Chain 81, including Astar, has a history of various test chains using the number 81 worldwide. Ultimately, our Japan Open Chain has been officially recognized as the mainnet by the Ethereum Foundation. The chain ID managed and certified by the Ethereum Foundation has become the de facto standard. It is common for other wallets to adopt it as the official one. Therefore, we regret to inform you that it seems necessary to re-establish other test chains with new IDs. Additionally, the Japan Open Chain testnet was initially set up with the number 99999. However, it was discovered that this chain had already been registered with the Ethereum Foundation as another test chain, leading us to re-establish it with the chain number 10081. Since then, we have registered it as the test chain number 10081 with the Ethereum Foundation.”

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@Maarten @Gaius_sama
We got answer from JOC.
How about Astar Foundation ? Any Answer about it ? :pray: