Safety limits & sync protection
How 2sync protects your data with automatic safety checks
2sync includes automatic safety features that pause syncs when detecting potentially harmful operations. These protections prevent accidental mass deletions and duplicate creation, giving you a chance to review before changes apply.
What triggers a safety halt?
| Trigger | What happens | Solution |
|---|---|---|
| Multiple Deletion | Sync is about to delete more than 50% of synced items | Review the pending changes, turn the bypass on if the deletions are intentional |
| Duplicates | Sync is about to create multiple duplicate entries | Check your data source, turn the bypass on if the entries are expected |
When a safety halt triggers, the automation pauses and displays an error badge on your dashboard. No data is modified until you review and take action.
Safety halts exist to protect your data. Turn the bypass on only after confirming the pending changes are intentional, and turn it back off as soon as they have synced.
How does bypassing Auto-Stop work?
The control is a toggle in your automation's sync settings, labeled Bypass Auto-Stop for significant data changes. It stays on until you switch it off yourself. Nothing resets it after a sync, so treat it as a door you open and close, not a one-time approval.
- Open the automation that triggered the halt
- On the dashboard, open the error and click more details to see which items the sync was about to change
- If the changes are intentional, turn on Bypass Auto-Stop for significant data changes in the sync settings
- If the automation shows Paused (Errored), click Resume. 2sync pauses an automation after four consecutive failed syncs, and a paused automation never restarts on its own, bypass or not
- Let the sync run and check that the change landed the way you expected
- Turn the toggle back off
Step 6 is the one people skip, and it is the one that matters. While the toggle is on, every sync runs with both safety checks disabled, not just the next one, and 2sync also skips the extra pass that re-checks each deletion candidate against the app before halting. A filter or field-mapping mistake weeks later then deletes items with nothing left to stop it.
The item list behind more details shows bare item IDs unless detailed activity logs are turned on, which they are not by default. To get titles, dates, and links instead, enable Opt-in for detailed activity logs on the activity logs page. The setting applies to errors recorded from that point on, so the next halt carries the readable list.
When do safety limits commonly trigger?
Safety halts are expected in certain situations:
Large initial syncs: When you first connect a database with existing data, the sync may flag bulk operations as potentially harmful. For example, connecting a Google Calendar with 500 events triggers a creation halt because 2sync would add all 500 items at once.
Filter changes: Updating filters can make previously synced items fall outside the new criteria, triggering deletion warnings. For example, switching your Google Calendar filter from "All calendars" to "Work only" means all personal events that were synced are now out of scope, so 2sync detects hundreds of pending deletions and halts.
Database restructuring: Renaming or reorganizing a Notion database may cause 2sync to see items as new rather than existing.
If you frequently trigger safety halts during setup, it usually means your configuration is changing rapidly. Once your automation stabilizes, halts become rare.
What are the size and rate limits?
Each plan has recommended limits to ensure reliable sync performance:
| Limit | Description |
|---|---|
| Notion database size | Recommended maximum varies by plan; larger databases sync slower |
| Google Contacts | Maximum 25,000 contacts per Google account (Google-enforced) |
| Email count | Limited per plan based on sync time window |
| Calendar events | Limited by your plan's time window setting |
| Relation & People properties | Up to 100 linked items written to Notion per property; Notion's API returns only the first 25 when read back |
When you exceed these limits, 2sync displays a specific error code. You can resolve it by reducing the sync time window, applying filters to narrow the scope, or upgrading your plan.
See Error Codes & Troubleshooting for the full list of size and rate limit errors and their solutions.
Relation and People properties (calendar attendees linked to contacts, contact groups, email recipients) hold up to 100 linked items written by 2sync. Notion's API returns only the first 25 items of these properties when 2sync reads a page back, so for lists longer than 25 items, 2sync keeps the connected app as the source of truth and writes in that direction. A partial read can never remove attendees or members you didn't change. To edit items beyond the first 25, make the change in the connected app rather than in Notion. See relations for how this affects attendee and contact mapping.
If a safety halt persists after you turn the bypass on, or you're unsure whether the pending changes are safe, see When to contact support.
Related
- Error codes for specific error messages and solutions
- Sync problems for general troubleshooting
- Rate limits and retries for API rate limit details
- Plans & pricing for plan limits and time windows
- Connection issues for authentication and connection troubleshooting