A new release of our favourite wallet (do those guys ever rest?). From the release notes:
Daedalus 3.1.0 delivers support for the upcoming ‘Cardano app for Ledger’ hardware device functionality and is required for continued use of Daedalus with Ledger hardware devices . This is to support users who upgrade their Cardano app on their Ledger hardware wallet device. This release also enables searching for stake pools by stake pool IDs and the display of stake pool IDs in the Delegation wizard.
https://iohk.zendesk.com/hc/en-us/articles/900004061886
For more details head over to the site. As ever just open Daedalus to be prompted to upgrade.