Custom skinpack is invisible

Solution 1:

Moments ago I had a similar problem and got it fixed:

You are missing a "," in your presume skins.json file, here:

    {
        "localization_name": "Jacket",
        "geometry": "geometry.humanoid.customSlim",
        "texture": "Jacket.png",
        "type": "free"
    } {
        "localization_name": "Halloween1",
        "geometry": "geometry.humanoid.customSlim",
        "texture": "Halloween1.png",
        "type": "free"
    }

As you can see, you are missing a comma between the two.
And just in case you don't see it and are confused, here is a comparison to the correct way to put it:

       {
            "localization_name": "Jacket",
            "geometry": "geometry.humanoid.customSlim",
            "texture": "Jacket.png",
            "type": "free"
        }, {
            "localization_name": "Halloween1",
            "geometry": "geometry.humanoid.customSlim",
            "texture": "Halloween1.png",
            "type": "free"
        }