A protocol update to add support for delegation and updated smart contracts will take effect on testnet on May 23, 2022.
New node software compliant with the protocol update has already been released for Linux, Windows, and MacOS here. Node runners must upgrade their nodes before the new protocol takes effect. Old nodes will stop processing new blocks at that point.
For more details on the protocol update, see concordium-update-proposals.
The protocol update on testnet is in preparation of a similar protocol update on mainnet in June 2022.