See Use Converted Database.

When Clinics is turned on, patient assignment to a clinic determines the default clinic used for billing, claims, payments, and adjustments. During Conversions, any patients not already assigned to clinics will be assigned to a clinic named Conv_Unassigned. We recommend identifying these patients, then assigning them to the correct clinic as soon possible after a conversion. To help you identify these patients, we provide a query in your Query Favorites: Conv - Patients in Unassigned Clinic.

In the Main Menu, click Reports, then User Query Favorites.

Double-click on the Conv - Patients in Unassigned Clinic query to run it.

For each patient listed, go the Edit Patient Information Window and assign a clinic.

Once all patients have been assigned an actual clinic, delete the Conv_Unassigned clinic.

1. In the Main Menu, click Lists, Clinics (Clinic List).
2. Double-click the Conv_Unassigned clinic.
3. Click Delete.

Resource: Post Conversion Checklist (PDF)