If you have troubles since the update to WordPress 4.5 please read this post before opening a new thread.
According to google page speed suggestion, the files should be combined into as few files as possible for faster loading.
Need help to combine them without error. Thanks
You can use cache plugins like W3TC or Super Cache (I prefer W3TC) to minify and combine js files.
Super Cache can’t combine the files
no luck with W3TC ; css error.