mongoose $inc findByIdAndUpdate failed
In your app's heroku logs , this line
Error: Can't set headers after they are sent.
you are sending response but without return statement.so if error occurs for some reason, it falls in the if check (your code):
if(err) res.json({error: err});
but it will not exit the process and next part also executes where you are also returning the response.
res.json(c).send({modif: c.modif});so the right way to send response is
router.put('/:id', function(req, res, next) { models.rappel.findByIdAndUpdate(req.params.id, {$inc: { modif: 1}}, {new: true}, function(err, c){ if(err) return res.json({error: err}); return res.json(c).send({modif: c.modif}); }); });