Duplicate Contact Merge Fails: How to Troubleshoot

This article covers errors when using the Duplicate Check & Merge tool (Settings > Fields & Data > Duplicate Check and Merge), including "Could Not Dupe Match Those Two Objects" and merges that fail after you click Merge. It explains what each means and how to resolve it. Only System Admins and Admins with the Data permission can use this tool. To fix a merge that completed incorrectly, see Fix an Incorrect Duplicate Merge.

💡Quick Answers

What does "Could Not Dupe Match Those Two Objects" mean? The system can't locate one or both contact IDs you entered. Verify both IDs, paste only the ID (no URL or slash), and confirm both records still exist.
Where do I find a contact's ID? Open the contact record; the ID is in the URL after /contacts/. Copy that exact string with no extra characters.
My merge fails after I click Merge. Why? Common causes are that one contact has a Billing Account, the records have conflicting auto-generated ID fields, or the record order needs swapping.
Is a merge reversible? No. Merging is permanent. Always review the side-by-side Dupe Check before merging. To fix an incorrect merge, see Fix an Incorrect Duplicate Merge.
Which record's data wins? The First Record ID. Its values win on conflicts; the second record's unique data still carries over, and merging never deletes data.
Match strength says Unknown or Weak. Can I still merge? Yes, if you have confirmed they are true duplicates. Match strength is only a guide.

Error: "Could Not Dupe Match Those Two Objects"

The "Could Not Dupe Match Those Two Objects" error means the system cannot locate one or both of the contact IDs you entered. Work through these:

Verify both contact IDs are correct.
Paste only the ID, with no extra characters, prefix, or trailing slash.
Confirm both contact records still exist in the system.

ID Examples:

✅ Correct: 81f56326-14f4-11e9-86f2-bc764e10a9f7

❌ Incorrect: contacts/81f56326-... , a trailing slash, or the full contact URL.

Resolve a Failed Merge

If the Dupe Check comparison worked but the merge itself fails, it is usually one of these:

A contact has a Billing Account: Contacts with a Billing Account need extra steps before merging. See Billing: How-to Merge or Delete Contacts with Billing Accounts.
Conflicting auto-generated ID fields: If your site uses auto-generated IDs (from an SIS or integration), the two records may have conflicting IDs. Remove the ID from one record, then retry the merge.
Record order: Sometimes reversing the order resolves it. Swap the First Record ID and Second Record ID and try again.

Match Strength is Unknown or Weak

Match Strength is calculated from weighted fields like name and birth date, so even small differences lower the score. It is only a guide. If you have confirmed the two records are true duplicates, even if the Match Strength is Unknown or Weak, you can merge them regardless of the score.

For reference:

Score	Match Strength
0-124	Unknown (unlikely to be duplicates)
125-149	Weak Match
150-224	Medium Match
225-300	Strong Match (likely duplicates)
301+	Herculean Match (almost certain duplicates)

Before You Merge

The First Record ID wins on conflicting fields; the second record's unique data carries over. Merging never deletes data.
Always click Dupe Check and review the side-by-side comparison before merging.
Merging is irreversible. If you merge the wrong records, see Fix an Incorrect Duplicate Merge.

Contact Finalsite Support

If the merge still fails after these steps, submit a request to Finalsite Support and include:

Both contact IDs. Exactly as you entered them.
The exact error message. Copy and paste or screenshot.
Billing status (if applicable). Whether either contact has a Billing Account.
Integration IDs. Whether the records use auto-generated IDs from an SIS or integration.
What you tried. Verifying IDs, swapping order, or removing an ID.

Additional Resources