Release Notes for Safari Technology Preview 101

Safari Technology Preview Release 101 is now available for download for macOS Catalina and macOS Mojave. If you already have Safari Technology Preview installed, you can update in the Software Update pane of System Preferences on macOS.

This release covers WebKit revisions 255473-256576.

Web Inspector

  • Added a special breakpoint for controlling whether debugger statements pause in the Sources tab (r255887)
  • Changed to encode binary web socket frames using base64 (r256497)
  • Fixed elements closing tag showing reversed in RTL mode (r256374)
  • Fixed the bezier editor popover to be strictly LTR (r255886)
  • Fixed dragging handles in the easing popover selecting sidebar text (r255888)
  • Updated some cookie table column headers to not be localizable (r255896)


  • Corrected TextTrack sorting with invalid BCP47 language (r255997)
  • Fixed AirPlay sometimes stopping after 60 minutes of playback (r255581)

Apple Pay

  • Redacted billing contact during payment method selection (r256071)


  • Added support for BigInt literal as PropertyName (r256541)

Web Animations

  • Fixed accelerated animations freezing on a render tree rebuild (r255663)
  • Fixed an event loop cycle between an animation finishing and it being removed from GraphicsLayerCA (r256181)
  • Fixed an issue where out-of-view transitions could trigger high memory use (r256095)
  • Prevented playing an accelerated animation that was canceled before it was committed (r255810)


  • Changed authenticatorGetAssertion to be sent without pinAuth if user verification is discouraged (r256001)


  • Aligned getDisplayMedia() with standards specifications (r256034)
  • Fixed not processing newly gathered ICE candidates if the document is suspended (r256009)


  • Fixed CSS rules with the same selector from several large stylesheets getting applied in the wrong order (r255671)


  • Fixed pages that trigger a redirect sometimes getting left blank (r256452)


  • Disallowed setting base URL to a data or JavaScript URL (r256191)
  • Fixed highlight text decorations to work with all decoration types and colors (r256451)
  • Implemented OffscreenCanvas.copiedImage (r256505)
  • Added standard gamepad mapping for GameControllerGamepads (r256215)
  • Tightened up stylesheet loading (r255693)
  • Fixed quantifiers after lookahead assertions to be syntax errors in Unicode patterns only (r255689)
  • Fixed \0 identity escapes to be syntax errors in Unicode patterns only (r255584)


  • Fixed iteration of cursors skipping records if deleted (r256414)

Back-forward Cache

  • Updated to remember if legacy TLS was used in the back-forward cache (r256073)