Create Object Class

When creating an object class, the database to which you are adding it cannot be in use.

Right-click the geodatabase in ArcCatalog and select New > Table.
Enter the table name both in the Name and Alias fields. The Name and Alias fields cannot contain spaces or special characters.
Click Next.
Enter the attribute field names that you want to transfer from the Origin to the Destination, and select the Data Type for each field.

NOTE: The field names cannot contain spaces or special characters.
Click Finish to add the new table to the geodatabase.