Developers deploy fix after Ethereum's Pectra upgrade hits snag on Sepolia testnet

Ethereum’s much-anticipated Pectra upgrade ran into another hurdle in its latest testnet release earlier on Wednesday. However, developers have identified the issue and rolled out a fix.

“We’re investigating an issue caused by the custom deposit contract on Sepolia,” Ethereum Foundation Protocol Support Lead Tim Beiko said in a message on X on Wednesday. “This has caused some EL clients to have issues including transactions in blocks.”

In other words, the Pectra deployment on Sepolia seems to have broken the testnet, preventing blocks from registering transactions. Thus, the testnet was essentially down for about five hours. 

The issue appears to have stemmed from a quirk of Sepolia’s deposit contract, which “emits” data related to a transaction’s transfer and deposit rather than bundling that into one message. 

“Some execution clients choked on it, txs stopped getting included,” CoinDCX executive Rohit Jain said on X. 

Approximately six hours after the error was spotted, Beiko noted that a hotfix had been found. “Client teams have coordinated on a fix and are trying to deploy it to validators right now. If this works as expected, we'll have a longer update out shortly,” he said. 

According to Etherscan data, the testnet began propagating blocks with transactions about an hour before publication time. 

This is not the first time a Pectra upgrade deployment has suffered an issue. On Feb. 24, the rollout on the Holesky testnet failed due to a misconfiguration among validators that led to a chain split. Ethereum developers now expect that activation to be finalized in at least two weeks. 

A mainnet rollout of Pectra— considered one of Ethereum’s most ambitious forks since the network’s switch to proof-of-stake — will only be attempted after the Holesky and Sepolia testnets are successfully upgraded. The Ethereum Foundation had targeted early April for the mainnet release, though that may be pushed back to make the testnet issues will not be replicated. 

Pectra introduces various improvements to boost Ethereum’s scalability, security and usability. Key changes include improvements in account abstraction through EIP-7702, raising the upper limit for validator stakes from 32 to 2,048 ETH via EIP-7251 and increasing the maximum blob count to advance rollup scalability through EIP-7691.