CalendarAgent is the background process that syncs the Calendar app with iCloud, Google, Exchange and other calendar accounts on earlier versions of macOS; it's part of macOS and safe. On a Mac with macOS 26.5 we found no CalendarAgent at all, and Calendar's background access ran in a process called calaccessd instead.
Last reviewed · 1 source
One Mac, macOS 26.5 (25F71) on Apple silicon, read with ps and codesign on October 29, 2026
| Path | None to show |
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| Note | No CalendarAgent process or launch agent on macOS 26.5; only com.apple.calendar.CalendarAgentBookmarkMigrationService.plist remains. Calendar's background access ran in /System/Library/PrivateFrameworks/CalendarDaemon.framework/Support/calaccessd (your user account, com.apple.calaccessd). |
CalendarAgent is the macOS background process that manages calendar data synchronization between the Calendar app and your configured calendar services, including iCloud, Google Calendar, Microsoft Exchange, and CalDAV servers. It handles fetching new events, pushing local changes, processing calendar invitations, and delivering event notifications and alerts on earlier versions of macOS. On a Mac running macOS 26.5 (checked October 29, 2026) there was no CalendarAgent process or launch agent; Calendar's background access ran in calaccessd instead.
High CPU usage from syncing a very large calendar with thousands of events
Constant network activity from CalendarAgent repeatedly trying to reach an unreachable calendar server
Excessive memory usage when processing calendars with complex recurring event patterns
Duplicate event notifications or missed reminders caused by sync conflicts
Go to System Settings > Internet Accounts and verify that all calendar accounts show a healthy status. If any account has a warning icon, re-enter the password. CalendarAgent often consumes high CPU when it cannot authenticate with a calendar server and enters a retry loop.
Quit Calendar, then run 'rm -rf ~/Library/Calendars/Calendar\ Cache*' in Terminal. Reopen Calendar. CalendarAgent will rebuild the cache by re-downloading all calendar data from your configured servers. This resolves most sync corruption issues.
In Calendar app, go to Calendar > Settings > Accounts. For each account, check the 'Events' dropdown and set it to a shorter sync range (such as 'Events from last 6 months' instead of 'All events'). This significantly reduces the data CalendarAgent needs to process and sync.
Run 'killall CalendarAgent' in Terminal. The system will restart it automatically when Calendar data is needed. This clears stuck sync operations and forces CalendarAgent to re-establish connections to all calendar servers.
CalendarAgent briefly spiking when you open Calendar or receive a new invitation is normal. Be concerned if it keeps using more than 30% CPU for a long stretch, especially when Calendar is not open. This usually indicates a sync loop with a calendar server — check your internet accounts for authentication errors. Also be concerned if CalendarAgent is generating excessive network traffic to non-calendar servers.
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No. CalendarAgent is a legitimate Apple system process that handles all calendar synchronization on macOS. It is code-signed by Apple and is part of the Calendar framework. It runs in the background to keep your calendar events synced across your devices and deliver event notifications. Seeing it in Activity Monitor is completely normal.
High CPU from CalendarAgent is typically caused by one of three things: syncing a very large calendar for the first time, a sync loop caused by an authentication failure with a calendar server, or processing a corrupted calendar cache. Check System Settings > Internet Accounts for authentication errors first, then try resetting the calendar cache if the issue persists.
You can temporarily stop it with 'killall CalendarAgent,' but macOS will restart it when Calendar data is needed. If you do not use the Calendar app, you can remove calendar accounts from System Settings > Internet Accounts to minimize CalendarAgent's activity. However, the process itself cannot be permanently disabled as it is a core part of macOS.
Yes. CalendarAgent syncs with any calendar service configured in System Settings > Internet Accounts, including Google Calendar, iCloud, Microsoft Exchange, and any CalDAV-compatible server. When you add a Google account and enable Calendar syncing, CalendarAgent handles all background communication with Google's calendar servers.
On macOS 26.5, where CalendarAgent no longer exists, calaccessd is the Calendar background process you'll see running. It runs for the logged-in user from /System/Library/PrivateFrameworks/CalendarDaemon.framework/Support/calaccessd and is signed by Apple (identifier com.apple.calaccessd).
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