So what most probably happened is that FileReader.readAsBinaryString()° defaults to FileReader.readAsText()°° since it's deprecated. At least that is what I saw

So what most probably happened is that FileReader.readAsBinaryString()° defaults to FileReader.readAsText()°° since it's deprecated. At least that is what I saw in Chromium. As soon as I used readAsArrayBuffer the problem went away. °) https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsBinaryString https://developer.mozilla.org/en-US/docs/Web/API/FileReader/... °°) https://developer.mozilla.org/en-US/docs/Web/API/FileReader/readAsText https://developer.mozilla.org/en-US/docs/Web/API/FileReader/...