Stacks, one of the first Bitcoin layer 2 networks, is back to producing blocks after suffering a roughly nine-hour outage on Friday.

Core developers continue to monitor the behavior of miners closely as the delay in Stacks’ block production was “due to unexpected mining behavior combined with a Bitcoin reorg,” according to @StacksStatus, an account on X dedicated to providing network updates for the blockchain.

Stacks produced block #153917 at 12:12 a.m. EST and #153918. at 9:20 a.m., a more than nine-hour gap. (
Stacks produced block #153917 at 12:12 a.m. EST and #153918. at 9:20 a.m., a more than nine-hour gap. (

A Bitcoin developer, who goes by @Mononautical, on X noted that Bitcoin at block height #847849 had a stale block, which “is consensus valid, but not part of the main chain because miners chose to build on a different block at the same height.” Sometimes two or more miners mine a block at the same time. Since the chain can only be built on a single block, one has to be abandoned, resulting in a stale block that is not included in the Bitcoin blockchain.

Unchained reached out to Stacks co-creator Muneeb Ali for an explanation of why the outage lasted nine hours, but had not heard back by press time.

At the time of Stack’s block #153917, the last block produced before Stack’s outage, the price of STX was hovering at $2.10 and at the time of writing, STX is trading at $1.92, a 8.5% drop since the outage.

The halt on Friday was not the first time Stacks had a delay in its block production. April 2 saw “unexpected mining behavior combined with a few slower Bitcoin blocks”  according to @StacksStatus, referring to gaps between blocks ranging from three minutes up to 51 minutes over the course of four and a half hours that day. On March 17, the network also had inconsistent block production for a few hours, per @StacksStatus.