When are Browser UI sites updated? 

Environment:

Browser User Interface (BUI) Updates

Resolution:

Browser User Interface is a single-version service that is updated without user impact. Agents can continue to work during deployment and can take the update at their leisure.  We consider the service continuous delivery and may perform updates as needed. 

Please see below for planned future updates and with release notes for past releases linked:

April Updates

Start dates and available details for each Update

Start Dates	Build	Release Notes	What's New
Non-production site deployment starts Mar 26th  Production site deployment starts Apr 2nd	3.20.03.20-b0018	Apr 2nd	n/a
Non-production site deployment starts Apr 2nd  Production site deployment starts Apr 9th	3.20.03.27-b0010	Apr 9th	n/a
Non-production site deployment starts Apr 9th  Production site deployment starts Apr 16th
Non-production site deployment starts Apr 16th  Production site deployment starts Apr 23rd
Non-production site deployment starts Apr 23rd  Production site deployment starts Apr 30th

March Updates

Start dates and available details for each Update

Start Dates	Build	Release Notes	What's New
Non-production site deployment starts Mar 5th  Production site deployment starts Mar 12th	3.20.02.28-b0014	Mar 12th	Mar 12th
Non-production site deployment starts Mar 12th  Production site deployment starts Mar 19th	3.20.03.06-b0004	Mar 19th	Mar 19th
Non-production site deployment starts Mar 19th  Production site deployment starts Mar 26th	3.20.03.13-b0013	Mar 26th	Mar 26th

All customers will receive these updates with zero down time.  At the time the update is pushed, all agents that are logged in will receive a message box that allows them to choose to accept the update or wait until they finish their current open work:

The first user that accepts the update for a specific interface will incur a cache hit, the cache for that interface will be re-created and that single user will experience a longer than usual refresh, but no other user of that interface will experience that lag.

Agent Browser User Interface is supported for the last five (5) Oracle Service Cloud releases for all customers.  Therefore to maintain Browser User Interface support, you must upgrade Oracle Service Cloud at least once a year. In order to leverage the latest and greatest of Agent Browser User Interface, we recommend you join the Auto Update Program and stay on the latest version of Oracle Service Cloud.

Other answers with Browser User Interface information:
Answer ID 6950: Raising Browser UI application issues
Answer ID 6926: Requesting the Browser UI for Oracle Service Cloud sites
Answer ID 8173: Documentation for Supported Features in Browser User Interface