Hedera will be upgrading the Testnet to v0.18.0 (release notes: https://hedera.io/release-notes
) on Thursday, September 23rd 2021 at 16:00 UTC. The upgrade will take approximately 2 hours to complete, during which time all network services on the Hedera Testnet will be offline. This upgrade should not affect your project's compatibility or data. As a precaution, we always recommend preserving project data prior to any Testnet upgrade.