How to Fix Cin7 Core + QuickBooks Sync Errors in 2025
If you’ve ever seen your Cin7 Core and QuickBooks Online data go out of sync, duplicate customers, missing invoices, or endless error codes, you’re not alone. Sync issues between these two powerful systems are common, especially when settings drift or IDs change.
In this step-by-step guide, we’ll walk you through how to find, fix, and prevent the most common Cin7 Core and QuickBooks sync errors, so your systems stay connected, clean, and compliant.
Start with Your Sync History
Open the integration dashboard inside Cin7 Core or your QuickBooks Online app settings. This area shows you which syncs have succeeded, failed, or partially completed.
What to check:
Look for any red “X” or failed sync notifications.
Review timestamps, if a job ran twice or never completed, that’s your first clue.
Click “View History” to see what is synced (and what didn’t).
PRO TIP: Screenshot your sync history before making changes, so you have a reference point.
Need help integrating QuickBooks Online and Cin7 core?
Certum Solutions is here to help. Book a free consultation with our software experts today. Free Consultation
Review Your Integration Tabs and Error Logs
Inside Cin7 Core, open the Integrations tab. You’ll see all linked modules: Products, Suppliers, Customers, Invoices, and Orders.
If something isn’t syncing:
Check if the integration toggle was turned off or paused.
Look for modules that say, “not mapped”, that means data can’t find its match in QuickBooks.
Re-connect or re-authenticate any that has expired log-ins.
Need deeper support? Book a free consultation to see how Certum Solutions can help! QuickBooks Training Options
Run a Manual Sync and Compare Records
Once you’ve confirmed settings, run a manual sync. Then, head to QuickBooks Online and open the related record (e.g., customer or supplier) to compare.
If you see duplicates, one record in QuickBooks and one in Cin7 Core, delete or merge the extra before re-syncing.
PRO TIP: QuickBooks treats “Joe’s Tackle Shop” and “Joes Tackle Shop LLC” as different customers, even if they’re identical. Make sure your names, IDs, and addresses match exactly.
Fix Duplicate Records and Missing IDs
Every record in QuickBooks Online has an internal ID used for syncing. If you bulk-update, rename, or merge accounts, that ID changes and the Cin7 connection breaks.
How to fix it:
1. Find the item or contact in QuickBooks Online.
2. Note its unique ID (using the Audit Log or URL path).
3. Update the same ID inside Cin7 Core.
4. Re-sync records individually.
Once they match again, your integration should be complete without error.
Align Tax Rules and Payment Terms
Mismatched tax or payment settings are another top cause of sync errors.
Example:
Cin7 lists “Sales Tax 10%,” but QuickBooks calls it “10 Percent Sales Tax.”
Cin7 sets payment term “Net 30,” while QuickBooks says, “Due in 30 Days.”
The mismatch confuses both systems. Update the wording so they match exactly.
Review Imported Data for Conflicts
If you import data from CSVs or other apps, QuickBooks sometimes assigns new unique IDs. That can duplicate data already existing in Cin7 Core. Before importing:
Search QuickBooks Online to see if that record already exists.
Match reference numbers exactly.
Import small batches so you can test syncs between rounds.
Use QuickBooks’ Audit Trail to Verify Changes
QuickBooks Online keeps a hidden audit ID for every update. When sync errors occur, use that audit trail to trace which entries changed since your last sync.
If you’re editing thousands of records (like tax rules or product names), do it in small batches and re-sync each batch before moving on.
Avoid Over-Using Advanced Settings
Advanced options can help re-sync data, but they can also wipe out good data if used incorrectly.
Use these only when directed by support or when you understand exactly what they do.
Top Cin7 Core ↔ QuickBooks Sync Mistakes We See
Here are the issues we fix most often:
Running bulk updates in QuickBooks instead of Cin7 Core
Mismatched tax rules and terms
Duplicate supplier or customer names
Out-of-date integration API keys
No weekly sync audit schedule
Fix these early, and you’ll cut 90% of your sync problems.
Prevent Future Sync Errors
To help prevent future sync errors between QuickBooks Online and Cin7 Core, we recommend following these best practices:
Schedule a weekly manual sync audit.
Set reminders to update API connections before they expire.
Document your integration settings and share them with your team.
Train staff to edit records in the correct system (Cin7 vs QuickBooks).
Back up data before major imports or bulk changes.
When to Call an Expert
If you’ve fixed duplicates, resynced, and still see errors, it’s time for professional support.
Certum Solutions is a trusted Cin7 Core and QuickBooks partner; we help companies nationwide stabilize their integrations and avoid data loss.
Book a Free Sync Consultation: https://www.certumsolutions.com/book-consultation
Contact Us Today: https://www.certumsolutions.com/contact
Additional Resources:
Cin7 Core Software Overview: https://www.certumsolutions.com/cin7-inventory-software
QuickBooks Online Setup & Support: https://www.certumsolutions.com/quickbooks-online-setup-support
Inventory Management Solutions: https://www.certumsolutions.com/inventory-management
Business Operations Advisory: https://www.certumsolutions.com/business-operations
QuickBooks Online Training: https://www.certumsolutions.com/quickbooks-training
Cin7 Core Help Center: https://help.core.cin7.com/hc/en-us
QuickBooks Integration Support: https://quickbooks.intuit.com/learn-support/en-us