Steps to reproduce:

1. Create a new 3D URP project.
2. Install Window > Package Manager > Unity Registry > Visual Effect Graph.
3. In Package Manager, Visual Effect Graph > Samples > Learning Templates > Import.

Actual results: 6 errors similar to:
{code:java}
Problem detected while importing the Prefab file: 'Assets/Samples/Visual Effect Graph/17.0.3/Learning
Templates/Prefabs/TurntableWithBackdrop_VFX.prefab'.
The file might be corrupt or have a missing Variant parent or nested Prefabs. See details below.
Errors:
Prefab Variant problem. Missing Prefab Variant parent: 'TurntableWithBackdrop_VFX (Missing Prefab with guid: 0bc1879d774271a4bab62da6b2f6eac2)'
UnityEngine.GUlUtility:ProcessEvent (int,intptr,bool&)
{code}
and
{code:java}
Assertion failed on expression: 'prefabinstance.GetPrefabModification).m_TransformParent.IsValid'
Unity Engine.GUlUtility:ProcessEvent (int,intptr,bool&)
{code}
 

Expected results: No errors.

Reproducible with versions:

• 6000.1.0b1, 6000.0.33f1, 6000.0.26f1
• 6000.0.25f1 -> 2023.3.0a9, no console error will appear in the Editor UI, but the same errors can be found still in the Editor.log file.

Can’t test with versions: 2023.3.0a8 and below, no Learning templates available.

Tested on (OS): Windows 10

Notes:

• Errors are harder to notice in some versions as the console is cleared after the import occurs. This may also be a bug.
• This issue also happens if you select the button to install the Learning templates while you are creating a new VFX graph.