Error when trying to save new file in afterSaveFile

Parse Server 📡 Cloud Code
,
3

Thanks for the help, I moved everything into Job and changed what you wrote:

Parse.Cloud.job("createThumb", async (request) => {
    const { params, headers, log, message } = request;
    message("I just started");

    const file = params.f;
    const fileName = file.name();
    const fileData = await file.getData();

    const fileBuffer = Buffer.from(fileData, 'base64');
    const mimeInfo = await fileType.fromBuffer(fileBuffer);

    if (mimeInfo.mime.startsWith("image")) {
        const options = { percentage: 5, responseType: 'base64' };
        const thumbnail = await imageThumbnail(fileBuffer, options);
        const thumbfile = new Parse.File("thumb_" + fileName, { base64: thumbnail });
        try {
            await thumbfile.save({ useMasterKey: true });
        } catch (err) {
            console.log("Failed to save thumb; " + err);
            return false;
        }
    }
    message("I just finished");
    return true;
});

However it gets an error when saving the file: Failed to save thumb; ParseError: 130 Unauthorised!