# About The HertzFix **URL:** \ **Category:** BNB Smart Chain\ **Created:** [January 10, 2024, 4:11am UTC](https://forum.bnbchain.org/t/about-the-hertzfix/2400 "2024-01-10T04:11:58Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![brilliant-lx](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.bnbchain.org/brilliant-lx/32/812_2.png) [@brilliant-lx](https://forum.bnbchain.org/u/brilliant-lx)\ **Post date:** [January 10, 2024, 4:11am UTC](https://forum.bnbchain.org/t/about-the-hertzfix/2400/1 "2024-01-10T04:11:58Z")
# Background BSC-Erigon nodes failed to sync on 2023/11/27, they all got stuck on block [33851236](https://bscscan.com/block/33851236), keep printing the below logs(refer: [issue-254](https://github.com/node-real/bsc-erigon/issues/254)): ```auto [WARN] [11-27|06:27:04.533] [downloader] Rejected header marked as bad hash=0x022296e50021d7225b75f3873e7bc5a2bf6376a08079b4368f9dee81946d623b height=33851236 [WARN] [11-27|06:27:04.597] [downloader] Rejected header marked as bad hash=0x022296e50021d7225b75f3873e7bc5a2bf6376a08079b4368f9dee81946d623b height=33851236 [WARN] [11-27|06:27:04.847] [downloader] Rejected header marked as bad hash=0x022296e50021d7225b75f3873e7bc5a2bf6376a08079b4368f9dee81946d623b height=33851236 [WARN] [11-27|06:27:04.899] [downloader] Rejected header marked as bad hash=0x022296e50021d7225b75f3873e7bc5a2bf6376a08079b4368f9dee81946d623b height=33851236 [WARN] [11-27|06:27:04.926] [downloader] Rejected header marked as bad hash=0x022296e50021d7225b75f3873e7bc5a2bf6376a08079b4368f9dee81946d623b height=33851236 [WARN] [11-27|06:27:05.358] [downloader] Rejected header marked as bad hash=0x022296e50021d7225b75f3873e7bc5a2bf6376a08079b4368f9dee81946d623b height=33851236 ``` After some investigation, it turns out that it is a bug of the [BSC-Geth](https://github.com/bnb-chain/bsc) client, BSC-Erigon’s execution result is indeed correct. # The RootCause The bug was introduced by a feature called [SharedOriginStorage](https://github.com/bnb-chain/bsc/pull/792), which was merged on 2022/03/28 and released with [v1.1.9](https://github.com/bnb-chain/bsc/releases/tag/v1.1.9) on 2022/04/12. The BSC-Geth client has been running with this potential bug for more than one and half years before it finally triggered the bug. **SharedOriginStorage** was introduced to improve performance by prefetching the IO state and storing it in StateDB, so IO access could be more efficient. The `StatePrefetcher` module would try to load the IO slots into the `sharedOriginStorage` structure, in most cases it works. But there is a corner case, that is if a contract performed these operation in one block: `1.Prefetch IO -> 2.Suicided -> 3.Revived(Create2) -> 4.Accessed Prefetched IO`, then the issue would occur, since the revived contract would load the prefetched state which is no longer valid as it has been suicided already. # Impact To BSC Users It only impacts user of this contract: [Arb Bot:0x00000000001f8b68515efb546542397d3293ccfd](https://bscscan.com/address/0x00000000001f8b68515efb546542397d3293ccfd), if you do not interact with this contract then there is no impact to you. And as the contract keeps running suicide/create2 loop, its storage will reset time by time, it suicided again at block [33851765](https://bscscan.com/block/33851765), that is only 529 blocks after the issue occur. So likely most `Arb Bot` users are ok, only some of the user that interacted with it between `Nov-27-2023 06:17:41 AM +UTC` and `Nov-27-2023 06:44:08 AM +UTC ` could be affected. Especially these 2 transactions: [https://bscscan.com/tx/0x7eba4edc7c1806d6ee1691d43513838931de5c94f9da56ec865721b402f775b0](https://bscscan.com/tx/0x7eba4edc7c1806d6ee1691d43513838931de5c94f9da56ec865721b402f775b0) [https://bscscan.com/tx/0x5217324f0711af744fe8e12d73f13fdb11805c8e29c0c095ac747b7e4563e935](https://bscscan.com/tx/0x5217324f0711af744fe8e12d73f13fdb11805c8e29c0c095ac747b7e4563e935) # How Is It Fixed We introduced a hard fork fix called `HertzFix` in [release v1.3.4](https://github.com/bnb-chain/bsc/releases/tag/v1.3.4), the fix is simple, just disable SharedOriginStorage. The PR is [https://github.com/bnb-chain/bsc/pull/2025](https://github.com/bnb-chain/bsc/pull/2025). The HertzFix hard fork has already been enabled on mainnet since block [34140700](https://bscscan.com/block/34140700), which is `Dec-07-2023 08:11:33 AM +UTC`. And for BSC-Erigon, there is a hot fix patch, it has no choice but to hard code the bad state into database in order to keep consistent with the BSC Mainnet, see: [https://github.com/node-real/bsc-erigon/pull/261](https://github.com/node-real/bsc-erigon/pull/261) # Conclusion Client diversity is helpful to increase the chain’s security, but it needs lots of extra resource. But at least 3 clients are needed to make sure none of them would surpass 50%. Most of the blockchain projects may not have enough resource to maintain several clients, then simplify the protocol and code is also very important.