Error: Destroying assets is not permitted to avoid data loss

[founderio]

Loading Spriter2UnityDX in Unity 5.4.1f1 throws this error message when selecting & de-selecting the Settings.asset:

Destroying assets is not permitted to avoid data loss.
If you really want to remove an asset use DestroyImmediate (theObject, true);
UnityEngine.Object:DestroyImmediate(Object)
Spriter2UnityDX.SettingsEditor:OnDisable() (at Assets/Spriter2UnityDX/Editor/S2USettings.cs:32)

[Dharengo]

Weird, maybe 5.4 changed how DestroyImmediate works?

[attilix]

The same error occurs to me in Unity 5.5 , and no prefab will be created after I try to import the Spriter`s project into Unity

[CarlosHBP]

I'm using Unity 5.6.1f and this message shows sometimes after delete prefabs/animations.
I doing this all time, testing animations.
Sometimes reimport scml doesn't recreate the prefabs, but I just delete scml file and reimport a second time and works!