From Discord, posted by @jernej
We have released Sapphire 0.4.0-testnet and Oasis Core 22.2.6 for TESTNET . Any node operators running Sapphire on TESTNET please upgrade to Oasis Core 22.2.6 and update your node configuration to add the new version of Sapphire and restart your node in preparation of the upcoming TESTNET upgrade. See the updated TESTNET network parameters page for the link to the new releases: Testnet | Oasis Network Documentation. Thanks!