In the coming months, Goerli, Ethereum's first multi-client testnet, will stop being supported by client and EF testing teams. The Dencun network upgrade will be the last one implemented on the network.
Either three months after the Goerli Dencun activation, or one month after the Dencun mainnet activation, whichever comes later, teams will begin exiting their validators . Anyone relying on Goerli as a stable testnet should migrate elsewhere prior to this.
While Goerli staking is permissionless, client and testing teams' validators make up a supermajority of the stake. Their exits will therefore affect the stability of the network. Additionally, teams plan to use the occasion to test delayed finality, inactivity leaks and mass-slashings.
Application and tooling developers are encouraged to use Sepolia to test decentralized applications, smart contracts, and other EVM functionality. Its permissioned validator set provides a stable test environment. Alternatively, many local development environments allow for testing against copies of the Ethereum mainnet state.
Stakers and infrastructure providers concerned with protocol-level testing are encouraged to use the newly launched Holesky testnet, where anyone can run a validator. For validator setup testing, stakers should also consider the Ephemery testnet. This network resets weekly and enables lightweight end-to-end testing of the validator lifecycle.
Goerli is currently expected to be the first testnet to activate the Dencun upgrade. Once the Goerli network upgrade date is set, this post will be updated to reflect it. The upgrade will be announced on this blog, and you can sign up to receive an email alert here.
Goerli was launched and maintained in a way that is emblematic of the Ethereum community: a group of semi-random people showed up to solve a technical problem and ended up building a community as a result. Thank you to everyone who contributed to the network over the years!
One contributor, whom all would agree gave the testnet its soul, deserves a special shout out: Afri Schoedon, thank you for the care and love you gave Görli!
 The dual-deadline approach was chosen to allow client teams the time to deploy a fix to Goerli in the case where a bug with the network upgrade was found late in the deployment process.