Missing divider lines in MacOS Calendar

MacOS Calendar app has suddenly lost all lines between days (vertical) and hours (horizontal). Is this some idiot Apple GUI developer's idea or have I got a glitch? Running Tahoe 26.3.1 on an M2 Air.

MacBook Air, macOS 26.3

Posted on Apr 15, 2026 7:41 AM

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Question marked as Top-ranking reply

Posted on Aug 16, 2026 1:45 PM

It is a temporary rendering glitch, not an intentional design choice. There is no toggle switch in macOS to hide or show calendar grid lines, meaning the sudden disappearance of your vertical and horizontal hour dividers is a minor UI rendering bug in your current session. 


Try this

  • Force Quit: Quit the Calendar app completely (Command + Q) and reopen it.
  • Reboot: Restart your Mac to clear out system-level window server and UI cache glitches.
  • Toggle Views: Switch back and forth between Day, Week, and Month views to force the window frame to redraw.
  • Check for Updates: Update your system past version 26.3.1 if an incremental patch is available. 
2 replies
Question marked as Top-ranking reply

Aug 16, 2026 1:45 PM in response to Daveypez

It is a temporary rendering glitch, not an intentional design choice. There is no toggle switch in macOS to hide or show calendar grid lines, meaning the sudden disappearance of your vertical and horizontal hour dividers is a minor UI rendering bug in your current session. 


Try this

  • Force Quit: Quit the Calendar app completely (Command + Q) and reopen it.
  • Reboot: Restart your Mac to clear out system-level window server and UI cache glitches.
  • Toggle Views: Switch back and forth between Day, Week, and Month views to force the window frame to redraw.
  • Check for Updates: Update your system past version 26.3.1 if an incremental patch is available. 

Aug 16, 2026 3:04 PM in response to WheelieNick

Thanks WheelieNick, I've done all those things and I think I've got the lines back but they are so faint I'm hardly sure! This is the sort of thing I'm very critical of Apple for. I am an older but quite capable user but much text is too light in colour and weight and so many menus are hidden. Acting as an assistant to lesser skilled older people I hear this sort of criticism all the time.

Missing divider lines in MacOS Calendar

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