typeerror: app.use() requires middleware function

This worked with me:

app.use(multer({
  dest: path.join(__dirname, 'public/upload/temp')
}).any());

It worked in this way. delete this line,

app.use(multer({ dest: './uploads' }));

and use it as,

var multer = require('multer');
var upload = multer({ dest: './uploads' });

I'm too following the same course

Change:

//Handle File Uploads
app.use(multer({
  dest: './uploads'
}));

For something like:

app.use(multer({dest:'./uploads/'}).single('singleInputFileName'));

or

app.use(multer({dest:'./uploads/'}).array('multiInputFileName'));

And be aware to have something like:

<form action="/postPhotos" enctype="multipart/form-data">
    <input type="file" name="singleInputFileName">
    <input type="submit" value="Upload photo">
</form>

for the first case, or:

<form action="/postPhotos" enctype="multipart/form-data">
    <input type="file" name="multiInputFileName" multiple>
    <input type="submit" value="Upload photo">
</form>

For the second one, in your html.