Certification stopped on `mainnet` and `preview` network

[jpraynaud]

Why

Since 11/21/25 on the mainnet network and since 11/20/25 on all the preview networks, the certification of the transactions has stopped.

With the following error occurring during the import of the block with Pallas:

{
  "msg": "An error occurred, runtime state kept. message = 'Could not compute message during 'ready to sign → ready to sign' phase (current epoch Epoch(1123))'",
  "v": 0,
  "name": "mithril-signer",
  "level": 50,
  "time": "2025-11-21T08:26:23.434126833Z",
  "hostname": "1002d6085bef",
  "pid": 1,
  "src": "StateMachine",
  "nested_error": "Runner can not compute protocol message for signed entity type: 'CardanoTransactions'\n\nCaused by:\n    0: Signable builder service can not compute protocol message with block_number: '3790109'\n    1: PallasChainReader failed to decode raw block\n    2: Invalid CBOR structure: decode error: Invalid hash size\n\nStack backtrace:\n   0: <E as anyhow::context::ext::StdError>::ext_context\n   1: <mithril_cardano_node_chain::chain_reader::pallas_chain_reader::PallasChainReader as mithril_cardano_node_chain::chain_reader::interface::ChainBlockReader>::get_next_chain_block::{{closure}}\n   2: <mithril_cardano_node_chain::chain_scanner::chain_reader_block_streamer::ChainReaderBlockStreamer as mithril_cardano_node_chain::chain_scanner::interface::BlockStreamer>::poll_next::{{closure}}\n   3: tokio::runtime::park::CachedParkThread::block_on\n   4: tokio::runtime::context::runtime::enter_runtime\n   5: <tokio::runtime::blocking::task::BlockingTask<T> as core::future::future::Future>::poll\n   6: tokio::runtime::task::harness::Harness<T,S>::poll\n   7: tokio::runtime::blocking::pool::Inner::run\n   8: std::sys::backtrace::__rust_begin_short_backtrace\n   9: core::ops::function::FnOnce::call_once{{vtable.shim}}\n  10: std::sys::thread::unix::Thread::new::thread_start\n  11: <unknown>\n  12: __clone"
}

What

Investigate the source of the problem and apply a fix to restore certification of the transactions on all networks

How

• Investigate the source of the problem
• Fix the problem:
  • Deploy Cardano node 10.5.2:
    • release-mainnet
    • release-preprod
    • pre-release-preview
    • testing-preview
    • dev-preview
    • dev-follower-preview
    • dev-mainnet
  • Certification has resumed:
    • release-mainnet
    • release-preprod
    • pre-release-preview
    • testing-preview
    • dev-preview
    • dev-follower-preview
    • dev-mainnet