I set up Parity blockchain network using Ethereum on Azure template sold at market place. It had worked well before, but suddenly had stopped to create blocks. For example, when I deployed a contract, no block number was not issued. There is a warning message (Fallback to `BlockId::Latest) in the log file of Parity. 2020-08-06 08:19:54 UTC IO Worker #1 INFO import 2/25 peers 504 KiB chain 169 MiB db 0 bytes queue 10 KiB sync RPC: 0 conn, 0 req/s, 35 μs 2020-08-06 08:20:24 UTC IO Worker #1 INFO import 2/25 peers 972 KiB chain 169 MiB db 0 bytes queue 10 KiB sync RPC: 0 conn, 0 req/s, 35 μs 2020-08-06 08:20:53 UTC jsonrpc-eventloop-0 WARN parity_rpc::v1::impls::eth Fallback to BlockId::Latest 2020-08-06 08:20:59 UTC IO Worker #1 INFO import 2/25 peers 75 KiB chain 169 MiB db 0 bytes queue 10 KiB sync RPC: 0 conn, 21 req/s, 21 μs 2020-08-06 08:21:29 UTC IO Worker #2 INFO import 2/25 peers 75 KiB chain 169 MiB db 0 bytes queue 10 KiB sync RPC: 0 conn, 5 req/s, 34 μs Please help me to fix this issue.

Hi, As per the logs shared by you it looks like the node is unable to seal/propose a block. This can happen either if the validator contract has changed the node got dropped from list of validators. Can you please try restarting both the validator Vms in your resource group? This will result in running some setup automatically and might help in resuming mining. Please restart the first VM, once that is up, wait for a few mins and then restart the next VM. This is to ensure there there are no inconsistencies in the blockchain resulting from concurrent restarts.

No block created at Ethereum on Azure

Accepted answer

Shrc-MSFT 226 Reputation points

2020-08-26T17:54:22.337+00:00
Hi, As per the logs shared by you it looks like the node is unable to seal/propose a block. This can happen either if

the validator contract has changed

the node got dropped from list of validators.

Can you please try restarting both the validator Vms in your resource group? This will result in running some setup automatically and might help in resuming mining. Please restart the first VM, once that is up, wait for a few mins and then restart the next VM. This is to ensure there there are no inconsistencies in the blockchain resulting from concurrent restarts.
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Aoki Nobuaki 61 Reputation points

2020-08-28T02:55:12.587+00:00

I restarted VMs with 10 minutes intervals, and sent a transaction after 10 minutes of the last vm restat.
But no block is created.

I have more two questions about this restart of VMs.

(a) Does the time interval of VMs restart (a few minutes in the answer) depend on any parameters of Parity nodes, for example, the length of blocks?

(b) After the restart of VMs, how can I check the list of validator nodes is restored correctly?
I understand that the list of validator nodes is hold in a contract, and I don't know how to view it.

Shrc-MSFT 226 Reputation points

2020-09-01T07:22:05.863+00:00

Hi @Aoki Nobuaki

(a) Does the time interval of VMs restart (a few minutes in the answer) depend on any parameters of Parity nodes, for example, the length of blocks - No it doesn't. We recommend that to prevent simultaneous restarts of validators that can cause forks.

(b) After the restart of VMs, how can I check the list of validator nodes is restored correctly? - The parity version running in these nodes use validator contracts and does not explicitly list validators. You can try updating the contract using this link https://openethereum.github.io/wiki/Validator-Set-Tutorial-2 in case it has gotten corrupted.

Aoki Nobuaki 61 Reputation points

2020-09-18T07:03:09.477+00:00

The blockchain nodes cannot create a new block, so I cannot update the validator set contract.

By the way, I modified the spec.json file to specify the validator address (selected from the account addresses of nodes) directly to the validators.list attribute,
and after restarting docker containers, I could deploy a contarct the nodes.

When I got the validator addresses by calling getValidators function of the validator set contract.
there were an address which was not in the account addresses of the nodes.
Does the addresses which validator set contract manages match always to the account addressed of the nodes?

And It seems that the account addresses are re-created after the boot of virtual machines,
and I guess this could be the cause of the no-block-creation problem,
and the problem could be recurred again if I restart virtual machines.
How can I restart them safely?

Shrc-MSFT 226 Reputation points

2020-09-29T12:48:57.037+00:00

Hi @Aoki Nobuaki

The rc.local config has been setup to bring up the poa network post restart with same validator address. So restart will not impact the account addresses. in your specific case, the additional address you may be seeing can be a old validator that was probably not removed from the network as mining was halted earlier. In case your block mining, transactions etc. are not impacted, you can ignore it.

Aoki Nobuaki 61 Reputation points

2020-10-02T00:57:54.797+00:00

II understand that restart of VM will not impact the account address.
Blocks are now created by modifying the addresses of validator nodes in spec.json.
I will see how it goes for a while.

Thank you.
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No block created at Ethereum on Azure

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