Alephium Hit by Network Slowdown ; Urgent Upgrade Underway

July 25, 2025 : Alephium , a sharded Layer 1 blockchain known for its Proof-of-Less-Work (PoLW) consensus, faced a significant slowdown in block production. The root of the issue was traced to a sharp decline in network hashrate compounded by a flaw in Alephium’s Difficulty Adjustment Algorithm (DAA). As a result, transaction processing on the network has noticeably slowed.

The Alephium core team has confirmed that an urgent network upgrade is being developed. The upgrade includes a new DAA mechanism currently under testing. The team has also promised to release a detailed post-mortem following the resolution of the incident. Until the fix is deployed, increasing block difficulty will continue to impact user experience. To ensure continued chain synchronization, node operators, miners, and mining pools are being advised to prepare for a mandatory update. A clear activation timestamp will be announced along with full instructions for node upgrades.

Systemic Challenges for Smaller Chains

While the Alephium slowdown exposes a technical flaw, it also highlights a broader issue faced by smaller PoW blockchains like Alephium: low network hashrate and limited miner participation. Unlike Bitcoin or Ethereum, such networks are more susceptible to performance fluctuations when mining power changes rapidly.

Alephium, which uses its BlockFlow technology to process over 20,000 transactions per second, has generally positioned itself as an energy-efficient and developer-friendly chain. However, this slowdown underscores how small shifts in hashrate can through the network, especially if the DAA isn’t responsive enough.