Block Hash Mismatches from Public Sidecar Instance on Kusama Asset Hub

[Imod7]

Description

A team is encountering frequent block hash mismatches (roughly every other day) between the public instance of Sidecar on Kusama Asset Hub (https://kusama-asset-hub-public-sidecar.parity-chains.parity.io/) and their local running Sidecar instance. The hashes eventually align after some time.

Examples

Block 10437072 (example from 2025-08-11), hashes from Sidecar public instance:

• Returned hash: 0xf1264fe9c87b93e734f46a2b8e3643ecda28cd76e7f6fa4eb217f77095bd35f0
• Expected hash: 0x03f40004c552694239b46fb0c2fe4f8c9d10ca096893cd2ad0a2a6637efb3988

Block 10168812
https://kusama-asset-hub-public-sidecar.parity-chains.parity.io/blocks/10168812?noAuthor=true

• Returned hash: 0x4025c34a05bb24f9e0b63c4d50e910dcf637d3859b3bd48ce640f2addf132913
• Expected hash: 0x1a09e6cbc81837e02937ff365d2f38cbbeb69e661e07a6cfd20c82c1bff60754

Other Examples

• Block 10081077
  • Returned Hash: 0xc58a4eda15cd317e02b80e8e48d332c76cff0af98a4fa63cd619dbbd7eb97ab4
• Block 10107012
  • Returned Hash: 0x063c4e93cebaaf403c94203073ab08eacdbabbb7a5f7f8b3426ed1109d8b4e93
• Block 10114100
  • Returned Hash: 0x7f1d3df7fba1ae50f54e0a1cd647cdba85020cd8b21027939c7988f34ad4bc2e
• Block 10117002
  • Returned Hash: 0x868ce40e699dec518f0dc641bd50b7e7e19cfe22d1cd0cab4de271c2cc786265
• Block 10117489
  • Returned Hash: 0xdae9acc16cc0ff028949cb1b3ebb389e946b2bcff3958b218b6aa437d6dbd78f
• Block 10121210
  • Returned Hash: 0x359e931cddafefab91cf16861dae0a438b400a85a08f66196d675d45450189fa
• Block 10125839
  • Returned Hash 0xa539a6f2ddc0a242a50db82b2d44ae21997f8f0c41f659ef53673f6c307cd72e
• Block 10148573
  • Returned Hash: 0x10a6aeb1d45b26444b370af870fd57b8746ffa92657fa0f0287df97d69c196c3
• Block 10153820
  • Returned Hash: 0x4e78f4e86242b83b06161ac3033a66cd8d92533e58fa8d681bb518387fdc02de
• Block 10185829
  • Returned Hash: 0x6fa176143f4667990ef52e47a8433fe6ae0930132fcc97d308437f4dc390160f

Steps to Reproduce

The issue could be reproduced with the following method:

• Create a script that runs for a period of one day and queries blocks:
  • from https://assethub-kusama.subscan.io/block/{height} and
  • from a local running instance of Sidecar.
• For each queried block, it compares the block hashes from the two sources and checks if they are the same.

Note

They never encounter mismatch when comparing with the public instance of Sidecar on Polkadot Asset Hub.

[TarikGul]

Okay so I did 2 different run through, I compared the /blocks/head with subscan, and I actually found subscan was giving back mismatched block hashes, then I did a public sidecar to local sidecar instance for asset hub kusama, and found no mismatches.