According to Cointelegraph: The Stellar Development Foundation (SDF) has advised a temporary halt to an upcoming smart contract upgrade on the Stellar blockchain, citing the recent discovery of a bug in Stellar Core v20.1.0.

In a January 27 blog post, the Foundation announced it had decided to "disarm [its] validators in support of postponing the Protocol 20 vote on Jan. 30 until after a bug fix." Despite acknowledging that the bug, found on Jan. 25, poses "little risk," SDF confirmed it could potentially affect multiple applications.
SDF is actively preparing a solution to the detected issue, with a fix expected to be ready within two weeks. Nonetheless, it stressed that the decision to upgrade the network will be made collectively, as non-SDF validators might still decide to push through with the Protocol 20 upgrade on the scheduled date.
"If validators opt to postpone the upgrade, we will coordinate to determine a future vote date once a new version of Stellar Core that contains a bug fix is released," the Foundation clarified.
Regardless of the decision, SDF affirmed its commitment to resolving this bug and continuing conversations with other validators on different channels.
The Protocol 20 upgrade requires a quorum of voting validators to be approved. As of December 2023, there were 43 validator nodes, according to Stellarbeat.io.