Unable to activate skin when trying to use a custom skin

I got an error saying unable to activate skin when trying to use a custom skin

Reproduction steps: 

1. Open launcher
2. Navigate to Java Edition, then the Skins tab
3. Click New Skin, name it, select the player model (in my case I select wide), under skin file click Browse, select the file, finally click Save 
4. Hover over the custom skin, click Use

Expected: Successfully change the skin to the custom one

What actually happened: The error below

Launcher log:

launcher_log.txt

Skin: