When attempting to copy an item, Sharegate displays the following error message:
The value 'My value' is unavailable. Please specify another value.
|Any error code ending with: -108|
The error should appear on a given property, for example, Property Status: The value 'My value' is unavailable. Please specify another value.
The error occurs because the specified value is not a valid choice for this column. The most common cause for this is if there was a value that was a valid choice in the past and that was used in some items, but it has now been removed from the list of valid choices.
Temporarily set the problematic column to allow fill-in choices while you perform the migration with Sharegate. You can do so by going on the destination list or library settings in SharePoint, then clicking on the column and setting "Allow 'Fill-in' choices" to Yes. This will allow Sharegate to enter any value in this column, so it will prevent errors stating that the value is not valid for this column.