Description
The input layer and append layer must have the same time type.
Solution
Verify that the layer you want to append has the same time type as the layer you want to append to.
For example, append instant time features to instant time features, and interval time features to interval time features.
Change the time properties of one layer to match the other.
For example, your input layer defines time type interval with a start and end time field. Your append layer defines time type instant with a single time field. Change your input layer to instant by defining a single time field, or change your append layer to interval by defining a start and end time field.
To learn more about setting time properties for feature layers, see Configure time settings.
To learn more about setting time properties in ArcGIS AllSource, see Set the time properties on data.