Could not parse as a valid SB2 or SB3 project.

When I tried to load a .sb3 file, I encountered the following error.

lib.min.js:181

{
    "validationError":"Could not parse as a valid SB2 or SB3 project.",
    "sb2Errors":[
        {
            "keyword":"required",
            "dataPath":"",
            "schemaPath":"#/required",
            "params":{
                "missingProperty":"objName"
            },
            "message":"should have required property 'objName'"
        }
    ],
    "sb3Errors":[
        {
            "keyword":"enum",
            "dataPath":".targets[1].isStage",
            "schemaPath":"sb3_definitions.json#/definitions/sprite/properties/isStage/enum",
            "params":{
                "allowedValues":[
                    false
                ]
            },
            "message":"should be equal to one of the allowed values"
        }
    ]
}

And I modify the isStage's value to 'false', it can be worked...

So... how to solve it

Reproduce the reported .sb3 loading failure and inspect the validation output in lib.min.js, focusing on targets[1].isStage and the SB2/SB3 schema checks. Determine whether the project should be accepted without manually changing isStage; done means the reported project loads or the validation behavior is clearly documented with a regression check.