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This error appears when Maestra detects an attempt to use a duplicate unique identifier. Re-registering a customer with a unique identifier that already exists in the system is not allowed — each technical ID can belong to only one customer.

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Why this happens

When you import customer data, the error shows up in two scenarios:
1

Maestra can't determine which customer to update

The system can’t reliably match the incoming record to an existing customer, so it tries to create a new one. But the technical ID in the incoming record is already taken by another customer, so creation fails.
2

The customer isn't found by the chosen identifier

Maestra falls through to creating a new customer, but the technical ID supplied for that new customer collides with an ID that already exists in the database.
In both cases, the underlying rule is the same: a technical ID is unique across the entire customer database, and Maestra refuses to assign one that is already in use.

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The same rule applies to “account access” contacts

The uniqueness restriction isn’t limited to technical IDs. Phone numbers and email addresses flagged as account access identifiers follow the same rule — you can’t reuse the same phone or email as an account access identifier for two different customers.
If you need to understand how Maestra decides which fields count as unique identifiers and how matching works during import, review the customer identifiers documentation for the full mechanism.

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How to fix it

  • Confirm which identifier you’re sending in the import and check whether it already exists on another customer profile.
  • If you intended to update an existing customer, use an identifier that uniquely points to that customer so Maestra can match instead of creating a new record.
  • If you intended to create a new customer, generate a technical ID that isn’t already in use.
  • For account access phones and emails, make sure the value isn’t already attached as an account access contact to a different customer.