Construction History Validation

>>> [WARNING] Construction history check - FAIL
> Mesh "{mesh_name}" has construction history!
> Automatic fix is available.
Make sure to delete all construction history before rigging the character.
Also, making any changes after the character is rigged will create unnecessary construction history that might break the character on the platform.
An automatic fix is available! By clicking on the
icon a pop up window will appear.
As stated in the window above, bypass fix might create unwanted side effects on the character.
Make sure to double check if the character and the rig works like it should after applying the fix.
If blendshapes have deformation order set to Post-deformation they will also fail history validation and they will be removed by the fix.
To change deformation order of blendshapes you can do the following:
  1. 1.
    Right-click the object with blendshapes and select Inputs > All Inputs from the marking menu.
  2. 2.
    In the List of input operations window that appears, middle-drag the deformers into the order you want them to occur.
In this case put blendshape node bellow the skin cluster.
More info at the following link.