# Two block reorg at height 941880

**URL:** https://bnoc.xyz/t/two-block-reorg-at-height-941880/97
**Category:** forks
**Tags:** fork
**Created:** [March 23, 2026, 4:25pm UTC](https://bnoc.xyz/t/two-block-reorg-at-height-941880/97 "2026-03-23T16:25:58Z")
**Posts on this page:** 1
**Showing post:** 20

<div class="post-metadata">

### Author: ![b10c](https://bnoc.xyz/user_avatar/bnoc.xyz/b10c/32/4_2.png) [@b10c](https://bnoc.xyz/u/b10c)
#### Post date: [March 26, 2026, 8:16am UTC](https://bnoc.xyz/t/two-block-reorg-at-height-941880/97/20 "2026-03-26T08:16:31Z")

</div>

A miner mining on Foundry shared the following stratum job data with me. I’ve anonymized it a bit.

| first job arrival timestamp | mining on block | duration on this tip |
| --- | --- | --- |
| 15:48:16.700 | 941880 Foundry | ~ 98s |
| 15:49:54.200 | 941881 AntPool (stale) | ~ 1s |
| 15:49:55.300 | 941881 Foundry | ~ 112s |
| 15:51:47.350 | 941882 ViaBTC (stale) | ~ 1.3s |
| 15:51:48.700 | 941882 Foundry | ~ 192s |
| 15:55:00.500 | 941883 Foundry | \> 5min |

* * *

My takeaway from this is:

- at 15.49:54, Foundry send a job building on top of the AntPool 941881 block, but switched to it’s Foundry 941881 block around 1s later
- then, at 15:51:47, ViaBTC found a block at height 941882, Foundry switched to this block, but after 1.3s switched to Foundry’s 941882

* * *

Foundry switching to their own block (e.g. with `preciousblock`) is a very reasonable thing to do for them. We know Foundry has been doing this for a while, and AntPool, for whatever reason, does not: [Mining Pool Behavior during Forks](https://b10c.me/blog/014-mining-pool-behavior-during-forks/)

This also shows that Foundry too saw the AntPool and ViaBTC blocks arriving first. However, it’s not unreasonable that a miner submitted a valid share even after the AntPool & ViaBTC blocks where known to the network. See e.g. [AntPool mines two blocks at height 925051](https://bnoc.xyz/t/antpool-mines-two-blocks-at-height-925051/60) where AntPool miners found two valid shares at a similar time.

---

_[View the full topic](https://bnoc.xyz/t/two-block-reorg-at-height-941880/97)._