Question posted in 
Our developed website uses WordPress as our CMS, but the problem is, the WordPress we are using are outdated (old version). so our IT Department told us to update the WordPress we are using to avoid security issues.
My question is, if we update the version of the WordPress we are using, is it possible that we can get error from the back-end? (PHP code)
We are planning to try it in the localhost before we update it live.
2
Answers
Yes, It can be possible to get an error after the WordPress update. because of some deprecated functions in WordPress and PHP version.
If you are using an older version of PHP then it can be possible to get an Error. But you can update your PHP version to set with your new WordPress.
So my advice is that first you set your WordPress site in localhost with PHP latest version and update it.
If your WordPress is very older it can be possible to get an error, but it doesn’t make you serious problem. Because these errors are more likely to be due to the lack of a PHP version. And it will be fixed by updating PHP
Best way is, you have a copy of website in localhost or in subdomain (dev.example.com) and test any code and update on it, after that apply to main websites.