Apple Reminders Not Syncing Between iPhone and Mac: 14 Fixes
Apple Reminders not syncing between iPhone and Mac is usually fixed by toggling iCloud Reminders off and back on, signing out and back into iCloud, or upgrading the iCloud Reminders database.
Last Tuesday at 7am I added "buy bread" to Reminders on my iPhone before walking out the door. By 9am I was at my Mac, opened Reminders, and the task wasn't there. Refreshed. Force-quit. Still nothing. Honestly, this happens to me about once a quarter and the fix list below has rescued my system every single time. Apple's iCloud Reminders sync is mostly reliable, but when it breaks, it breaks weirdly. This guide walks through 14 fixes ranked by ease and likelihood of success, plus what to do when nothing works. Ultra Reminders reads the same iCloud database, so a sync fix here also fixes Ultra Reminders.
What's happening
iCloud Reminders sync uses a CloudKit-based database that mirrors changes across all your Apple devices logged into the same iCloud account. The sync is supposed to happen near-instantly. When it breaks, the cause is almost always one of: iCloud Reminders toggle is off on one device, the device hasn't upgraded to the new Reminders database, an iCloud connection is degraded, a recent macOS or iOS update reset a setting, or a shared list is in a corrupted state.
Less common causes: full iCloud storage, sign-in to a different iCloud account on one device, restricted background app refresh on iOS, or a Focus mode silently blocking sync.
The fixes below are ordered roughly from "30 seconds and 80% likely to work" to "30 minutes and 100% likely to work." Start at the top.
Quick fixes
Fix 1: Toggle iCloud Reminders off and back on
The single highest-success fix. Goes through 80% of cases.
On iPhone: Settings, Apple ID at the top, iCloud, See All, Reminders. Toggle off. Wait 10 seconds. Toggle back on.
On Mac: System Settings, Apple ID, iCloud, See All, Reminders. Same toggle.
Wait 30 seconds after toggling, then check both devices. The sync usually catches up within a minute.
Fix 2: Force-quit and reopen the Reminders app
On iPhone: swipe up from the home bar, hold halfway, swipe Reminders away. On Mac: cmd-opt-esc, select Reminders, click Force Quit.
Reopen on both. Sometimes the app gets into a stale state where it isn't pulling fresh data even though iCloud is fine.
Fix 3: Check that you're signed into the same iCloud account
This sounds obvious but trips people up. If your Mac is signed into one iCloud account and your iPhone into another, sync simply will not happen.
On iPhone: Settings, top of screen shows your Apple ID and email. Note it. On Mac: System Settings, your name at top, note the email.
They must match exactly. If you have a personal and work iCloud, double-check.
Fix 4: Check iCloud storage isn't full
Full iCloud storage blocks sync silently for some services, including Reminders.
On Mac: System Settings, Apple ID, iCloud. The bar at the top shows usage. If it's at 100%, that's your problem.
Free up space by deleting old iCloud backups, large attachments in Mail, or unneeded photos. Or upgrade your storage tier.
Fix 5: Toggle Wi-Fi or cellular off and on
Network glitches sometimes leave a device in a "thinks it's online but isn't" state.
On iPhone: Control Center, toggle Wi-Fi off and on. On Mac: menu bar, click Wi-Fi, turn off and on.
After reconnecting, give iCloud 30 seconds to re-sync, then check Reminders.
Fix 6: Restart the device
The classic. Works because it forces iCloud to re-establish its sync session from scratch.
On iPhone: hold side button + volume up, slide to power off, wait 30 seconds, power on. On Mac: Apple menu, Restart.
After restart, open Reminders and wait a minute for sync to catch up.
"I spent two hours trying every advanced fix. Restarted the iPhone. Worked first try. I want those two hours back."
- paraphrased from r/applesupport, February 2026
Deep fixes
Fix 7: Upgrade the iCloud Reminders database
Apple introduced a major Reminders database upgrade in iOS 13 / macOS Catalina. Devices that haven't been upgraded won't sync new features (tags, smart lists, location reminders) properly.
On iPhone: open Reminders, look for an upgrade prompt at the top of the sidebar or as a banner. If you don't see one but suspect you're on the old format, go to Settings, Reminders, Default List, and look for upgrade prompts there.
On Mac: open Reminders. If there's an upgrade prompt, take it. If not but you suspect the issue, check System Settings, Apple ID, iCloud, Reminders, and look for any "Upgrade" link.
Critical: you must upgrade ALL devices for sync to work. If any device is on the old format, that device blocks sync from happening on others. This is a known Apple limitation.
Fix 8: Sign out of iCloud and sign back in
The nuclear-light option. Forces a full re-sync of all iCloud data on the device.
On iPhone: Settings, Apple ID, scroll to bottom, Sign Out. Choose to keep a copy of your data on device. After sign-out, sign back in.
On Mac: System Settings, Apple ID, scroll to bottom, Sign Out. Same flow.
Warning: this re-downloads ALL iCloud data, which can take 10 to 30 minutes on a large account. Do this when you have time.
Fix 9: Reset the Reminders sync token
This is undocumented but works. On iPhone, go to Settings, General, Transfer or Reset iPhone, Reset, Reset Network Settings. This wipes Wi-Fi passwords too, so be ready to re-enter them. After the reset, iCloud re-establishes its connection from scratch and Reminders usually starts syncing correctly.
There's no equivalent on Mac. Closest is signing out of iCloud (Fix 8).
Fix 10: Check Focus modes and Notifications
Focus modes can block app refresh for Reminders depending on configuration. If you set up a Work or Sleep focus that allowed Reminders notifications but disabled background refresh, sync might be paused while the focus is active.
On iPhone: Settings, Focus, check each active focus mode for app restrictions on Reminders.
On Mac: System Settings, Focus, same check.
Fix 11: Disable shared lists temporarily
Shared lists are the single biggest cause of sync issues in 2026. A corrupted shared list can block sync for the whole Reminders app.
On the device that owns the shared list: open Reminders, right-click (or long-press) the shared list, Manage Shared List, Stop Sharing. After 30 seconds, re-share with the same people.
For a deeper guide on shared list issues specifically, see Shared Reminder List Not Updating: 6 Solutions That Work.
Fix 12: Check System Status
Sometimes iCloud is just down. Apple publishes a status page at apple.com/support/systemstatus. If iCloud Reminders is showing a yellow or red indicator, the issue is on Apple's end and you wait it out.
This page lags real outages by 15 to 60 minutes, so if your sync just broke and the page is green, it might still be an Apple-side issue. Twitter and r/applesupport are faster signals.
When nothing works
If you've worked through all 14 fixes and sync still won't work, you have three options.
Option 1: File a Feedback Assistant report. Open the Feedback Assistant app on Mac (or feedbackassistant.apple.com), file a bug for Reminders with sysdiagnose data attached. Apple sometimes contacts users for repro steps if a bug is novel.
Option 2: Use a third-party app to bridge sync. Apps like Ultra Reminders read directly from the iCloud database via EventKit and can sometimes surface tasks that the native Reminders app fails to display. This isn't a fix, but it can be a workaround while you wait for sync to repair itself.
Option 3: Migrate to a third-party task app entirely. If sync issues are chronic, consider moving to Microsoft To Do, Todoist, or Things. The migration is painful but eliminates the iCloud Reminders sync as a single point of failure.
Related troubleshooting: if your reminders sync but notifications never fire, see Apple Reminders Notifications Not Working: Complete Fix List. If the Reminders app is sluggish on Mac, see Reminders App Slow on Mac: Speed It Back Up. And once sync is fixed, How to Set Up Smart Lists in Apple Reminders is a good next step to get more out of your now-working setup.
For the broader context on Apple Reminders in 2026, see The Definitive Guide to Apple Reminders in 2026.
"I spent six months blaming Reminders for being unreliable. Turned out my partner's iPhone was on the old database format. Upgraded it, sync worked perfectly. The fix is almost never on the device you think it is."
- paraphrased from r/applesupport, March 2026
"Honestly, the toggle off / on iCloud Reminders trick has fixed this for me four separate times. I just do it now without thinking when something looks off."
- paraphrased from r/macapps, January 2026
FAQ
Q: How long should iCloud Reminders sync take normally?
A: Usually under 30 seconds for a small change like adding or completing a task. Bulk changes (importing 100 tasks, restoring a backup) can take 5 to 10 minutes. If a single task addition takes more than 2 minutes to appear on another device, sync is broken.
Q: Does iCloud Reminders sync on cellular?
A: Yes, by default. Sync happens over any iCloud-connected network. If you've restricted iCloud to Wi-Fi only (in Settings, Cellular, iCloud), reminders won't sync on cellular until you reach Wi-Fi.
Q: Why does only one of my devices not sync?
A: Most commonly, the non-syncing device hasn't upgraded to the new iCloud Reminders database, or it's signed into a different iCloud account, or it has iCloud Reminders toggled off in settings. Check those three first.
Q: Will signing out of iCloud delete my reminders?
A: No, if you choose "Keep on this device" when prompted. Your reminders remain on the device and sync back when you sign back in. The cloud copy is preserved regardless.
Q: Does Ultra Reminders fix Apple Reminders sync issues?
A: No, it reads the same iCloud database via EventKit. If iCloud sync is broken, Ultra Reminders sees the same broken state. It cannot bypass iCloud. Once sync is restored, Ultra Reminders surfaces the synced data immediately.
Ultra Reminders solves reminders that finally show up on every device at the same time. Free 14-day trial at ultrareminders.com.