React | Facebook JS API : Error code 100 when trying to upload multiple images to my page feed

Question

In a first function, I upload multiple images to page-id/photos and receive a positive response with all the ids of these images.

The next part however is where I'm stuck; I am now trying to create a post with multiple images to my Facebook page timeline. However, I'm getting a weird error response claiming that I already have uploaded my images.

I've even followed Facebook's own example from their documentation using Open Graph Explorer, but that just returns another error

Function to send image:

(works without a problem)

sendFacebookImagePost(page) {
    const attached_media = []
    for(let i = 0; i < this.state.upload_imgsrc.length; i++) {
        let reader = new FileReader();
        reader.onload = (e) => {
            let arrayBuffer = e.target.result;
            let blob = new Blob([arrayBuffer], { type: this.state.upload_imgsrc[i].type });
            let data = new FormData()
            data.append("source", blob)
            data.append("message", this.state.fb_message)
            data.append("no_story", true)
            data.append("published", true)

            axios({
                method: "post",
                url: "https://graph.facebook.com/" + page.id + "/photos?access_token=" + page.accessToken,
                data: data
            })
            .then(response => {
                attached_media.push({media_fbid: response.data.id})
                if (attached_media.length === this.state.upload_imgsrc.length) {
                    this.sendFacebookPost(page, attached_media)
                }
            })
            .catch(error => {
                console.log(error);
            })
        }
        reader.readAsArrayBuffer(this.state.upload_imgsrc[i]);
    }
}

Function to send post:

(Here is where the error happens)

sendFacebookPost(page, attached_media) {
    let data = { 
            message: this.state.fb_message, 
            link: this.state.fb_link,
            attached_media: attached_media
            // this is what attached_media returns:
            // [
            //     {media_fbid: response.data.id},
            //     {media_fbid: response.data.id}
            // ]
        }
    axios({
        method: "post",
        url: "https://graph.facebook.com/" + page.id + "/feed?access_token=" + page.accessToken,
        data: data
    })
    .then( () => this.setState({fb_successMessage: "Post successful!", fb_errorMessage: ""}) )
    .catch(error => {
        console.log(error);
    })
}

Error code

error: {
    code: 100
    error_subcode: 1366051
    error_user_msg: "These photos were already posted."
    error_user_title: "Already Posted"
    fbtrace_id: "Cl9TUTntOZK"
    is_transient: false
    message: "Invalid parameter"
    type: "OAuthException"
}

My try on Open Graph Explorer

Answer 1

Problem solved.
The part that went wrong is where I add the following to my image post:
data.append("published", true) .

Apparently, images you want to use in a multi photo post have to be set to published: false before they can be used in a post. Otherwise, Facebook sees this as already uploaded.