Ethereum node operators have two new client releases to assess after Erigon and Teku published updates addressing execution-layer bugs, dependency changes and consensus-client maintenance. Erigon v3.5.5 is explicitly classified as a security and bugfix release, while Teku 26.8.0 is a recommended update containing bug fixes and breaking changes.
The distinction matters for operators running mixed Ethereum client configurations. Erigon’s update directly targets issues affecting block proposers, archive nodes and installations using an external consensus client, while Teku’s release changes legacy deposit-handling dependencies. Both updates affect operational reliability, but Teku 26.8.0 should not be described as a dedicated security release based on its official classification.
📢Erigon v3.5.5 released!
Security + bugfix release. Recommended for all users.
Block proposers: Fulu blinded-block panic fixed
Archive operators: logIndex regression fixed (v3.5.1–v3.5.4)
External CL users: payload timing fix
Plus 4 security bumps.Drop-in from v3.5.4, no…
— erigon.eth (@ErigonEth) August 12, 2026
Erigon fixes proposer panic and archive-node regression
In the official Erigon v3.5.5 release, developers recommend upgrading all users, particularly block proposers and archive-node operators. The release fixes a panic affecting Fulu blinded-block submissions, incorrect logIndex values on archive nodes and a payload-building timing problem when Erigon operates with an external consensus layer.
The blinded-block problem occurred because a successful Fulu Builder API response could return 202 Accepted with an empty body, leading Erigon to dereference a nil payload. Developers also corrected payload timing so building continues until the relevant slot rather than potentially freezing before that slot begins. These changes address proposer stability and execution-consensus coordination rather than altering Ethereum’s protocol rules.
Erigon v3.5.5 is a drop-in replacement for v3.5.4, meaning operators can upgrade without performing a complete blockchain re-sync. That reduces the operational cost of applying the fixes, particularly for archive nodes whose datasets can make full synchronization resource-intensive.
Teku removes legacy web3j deposit handling
Teku 26.8.0, released August 10, is described in its official GitHub release notes as a recommended update containing bug fixes and breaking changes. The most consequential change is the removal of Teku’s legacy web3j-based Eth1 deposit-log fetching, reflecting Ethereum’s transition toward finalized deposit-tree snapshots and EIP-6110 execution requests.
Teku v26.8.0 is now available!
This is a recommended update.
Key changes:
* NOTE: Review breaking changes in release notes.
* Removed library dependencies on web3j.Full details and downloads: https://t.co/1M9vl8kvFg
— Teku (@Teku_Consensys) August 11, 2026
The release removes several related command-line options and deprecated tooling, while also fixing Beacon REST API socket retention and an edge case affecting single-block BeaconBlocksByRange requests. Operators should review configuration compatibility before upgrading because 26.8.0 removes functionality rather than functioning as a purely transparent maintenance patch.
Teku also flags a known issue for archive nodes using the leveldb-tree database, where startup can become unusually slow. Those operators may need to avoid 26.8.0 until the issue is addressed, making the upgrade decision dependent on node configuration rather than universally automatic.
The releases reinforce the importance of maintaining both sides of the post-Merge client stack. Erigon v3.5.5 addresses execution and proposer reliability, while Teku 26.8.0 modernizes consensus-client dependencies and removes legacy interfaces that some operators may still rely on.
