Warning: Exception thrown by hook while handling onSetChildren: Invariant Violation: Item must have been set Invariant Violation: Item must have been set

[eos87]

Hey there, I was playing with these components and when I upload multiple files using dropzone and global progress bar it throws this warning:
Warning: Exception thrown by hook while handling onSetChildren: Invariant Violation: Item must have been set Invariant Violation: Item must have been set

React version: 15.5.4. Also tested with 15.4.2 and same warning.

Here is my example code:

import Dropzone from "react-fine-uploader/dropzone"
import ProgressBar from "react-fine-uploader/progress-bar"
import FineUploaderTraditional from "fine-uploader-wrappers"

let defaultUploaderProps = {
   chunking: {
        enabled: true
    },
    deleteFile: {
        enabled: false,
    },
    retry: {
        enableAuto: true
    },
    validation: {
        sizeLimit: 30000,
        itemLimit: 50
    }    
}

class MyDropzone extends React.Component {
    constructor(props) {
        super(props);

        let _uploaderProps = Object.assign({}, defaultUploaderProps, props.uploaderProps);
        this.uploader = props.uploader || this.getUploader(_uploaderProps);
    }

    static get defaultProps() {
        return {
            dropActiveClassName: "well-dropzone-active",
            multiple: true,
            uploaderProps: {}
        }
    }

    getUploader(uploaderProps) {
        return new FineUploaderTraditional({
            options: uploaderProps
        });
    }

    render() {
        let zoneProps = Object.assign({}, this.props);
        delete zoneProps['uploaderProps'];

        return (
            <div>
                <ProgressBar uploader={this.uploader} className="progress-bar-uploader" />


                <Dropzone className="well well-form-dotted"
                    uploader={this.uploader} {...zoneProps}>

                    <div className="fa-3x">
                        <i className="fa fa-cloud-upload"></i>
                    </div>
                    <strong className="fsize14">
                            Choose your files or drag them here
                    </strong>
                </Dropzone>
            </div>
        )
    }
}

export { MyDropzone }

And here are couple of screenshots just in case they are helpful
http://prntscr.com/fdlss2
http://prntscr.com/fdlt76

These are really nice components! Thanks for this :)

[rnicholus]

React isn't very good a providing consistently readable error messages. This is one of those. Research indicates this is a bug in React 15 that may be patched in 16.

[rnicholus]

Haven't heard anything further on this in a while. Perhaps a react issue since fixed? If anyone is still seeing this with a current react version and can identify where react fine uploader is at fault, I can reopen

[jfconde]

In the company I work for, we're using React 15.6.1 altogether with ExtJS (ExtReact). This bug is popping up all the time :/

[jfconde]

Also, due to the fact that we're using (and bound to use) ExtReact for our current project, we can't upgrade to 16.X either.

[rnicholus]

i haven't seen this issue myself. if you are still seeing it and figure out how to best address it, please post here

[jfconde]

I'll do if I can. We need to get this error out of the way in order to continue advancing, so I hope today or tomorrow we can come up with a fix or some explanation about the error, at least.

[askarhu]

Anyone had any luck with this? I got this error after making one simple change to the already working app and even if I backtrack the change it still shows that error.