'Download your facebook information' generates html to view your messages, but the href attributes contain wrong directory names.It can be solved quickly by 'lowerCase-ing' the href attributes that start with 'messages' path segment.

facebook_your_messages_html_fix.kt

import org.jsoup.Jsoup
import java.io.File

fun main(args: Array<String>) {
    val (srcFile, targetFile) = args
    val doc = Jsoup.parse(File(srcFile).readText())
    doc.select("[href]").toList().forEach {
        val pathSegments = it.attr("href").split("/").toMutableList()
        if (pathSegments[0] == "messages") {
            pathSegments[2] = pathSegments[2].toLowerCase()
            it.attr("href", pathSegments.joinToString("/"))
        }
    }
    File(targetFile).writeText(doc.toString())
}