Cardano's Vasil Hard Fork Testnet Hits “Critical” Bug Just Two Weeks Post-Launch
Cardano's Vasil hard fork testnet has hit a major snag, threatening the success of this year’s most anticipated upgrade for the network.

Cardano's Vasil Hard Fork Testnet Hits “Critical” Bug Just Two Weeks Post-Launch
On August 18, Cardano developer Adam Dean shared troubling updates on Twitter, revealing a significant issue with node version 1.35.2, which has disrupted the Vasil hard fork testnet that was successfully deployed on July 4.
🧵 (1/n) It's important to point out today that the #Cardano #Testnet is **catastrophically** broken due to a bug in Cardano Node v 1.35.2. This was the version that we had previously been told was "Tested and Ready" for the Vasil Hardfork. This bug was only discovered...
— Adam Dean (@adamKDean) August 18, 2022
The problem stems from several Cardano staking pool operators (SPOs), who, in their rush to upgrade the mainnet, inadvertently created incompatible forks, causing a drop in blockchain interaction density. This has rendered the current testnet unusable, as most SPOs upgraded to version 1.35.2 on the testnet, causing version 1.35.3 to become incompatible and unsynchronized.
As a result, Cardano is forced to roll out version 1.35.3 on two new testnets that lack the transaction history and block production of the previous testnets. Dean expressed his concerns about the rushed Vasil upgrade, suggesting that Cardano's network is nearing its breaking point.
(2/n) because operators rushed to upgrade on #Mainnet and it was creating incompatible forks and causing a decrease to chain density. #Kudos to @ATADA_Stakepool and @PooltoolI for doing the research of on-chain data to identify 1.35.2 v. 1.34.1 as the culprit...
— Adam Dean (@adamKDean) August 18, 2022
Dean is urging IOHK’s technical team and founder Charles Hoskinson to quickly deploy “Disaster Recovery” tools as initially planned for the testnet launch. This plan includes measures to mitigate long-term network partitioning or extended blockchain freezes.
(4/n) We are now testing 1.35.3 on two "new" testnets that do not have a block history like testnet (having gone through all previous Cardano HFC events there) or a simulation of multi-node-version blocks on the chain...
— Adam Dean (@adamKDean) August 18, 2022
In response to community reactions regarding the bug in testnet version 1.35.2, Charles Hoskinson defended the project, asserting that the code had been thoroughly vetted over several months, including by SPOs. The faulty code affecting the testnet has been removed.
(6/n) I'm calling on @IOHK_Charles and @IOG_Eng to develop and deploy the tooling necessary to "Disaster Recovery" the #Testnet as described here https://t.co/0Z35zDSyj3
— Adam Dean (@adamKDean) August 18, 2022
Hoskinson further explained that Cardano cannot sacrifice the community’s expectations for the Vasil hard fork by delaying it for months just to re-evaluate code that has been extensively tested and is functioning well. He reminded both SPOs and the community that decisions are collective, reinforcing Cardano's commitment to being a truly decentralized platform.
It's bizarre and alarmist seeing these videos floating around that things are being rushed with 1.35.3. The code in question has been thoroughly tested for months by everyone including SPOs. The code that was an issue on the testnet has been removed.
— Charles Hoskinson (@IOHK_Charles) August 19, 2022
You're the SPOs, you ultimately decide. I'm seriously tired of taking the blame on both sides. Cardano is decentralized. The people running the network ultimately decide upgrades not me.
— Charles Hoskinson (@IOHK_Charles) August 19, 2022