Cannot find file [Content_Types].xml in zip

Greetings. I’ve been using your library to read xls files with no issues. However when I try to read any xlsx file, I get the following error:

Uncaught (in promise) Error: Cannot find file [Content_Types].xml in zip at getzipfile (xlsx.js:2822) at getzipstr (xlsx.js:2833) at parse_zip (xlsx.js:20373) at read_zip (xlsx.js:20707) at Object.readSync [as read] (xlsx.js:20773)

I’ve tried to use different files, even changed the extension to .zip to confirm the existence of the [Content_Types].xml. Any ideas on how to fix this issue? Here is how I’m doing to the reading:

return new Promise((resolve, reject) => {
     fileReader.onerror = () => {
          fileReader.abort();
          reject(new Error("Error"));
    };

    fileReader.onload = () => {
          resolve(fileReader.result);
    };

   fileReader.readAsBinaryString(file);      
})
.then(r => { return read(r, {type: 'binary'}); })