I can understand that broken updates does cause bad impression in front of clients and I am really sorry for the same. However, we always suggest our customers to update the theme and plugin on a staging server. That way even if any issues comes up you can troubleshoot the problem without effecting the live website. We follow a rigorous testing internally to make sure we find out issues and fix them before releasing the updates. Each team member is required to test the update on there system or server and report the bugs. We are actually encouraged by our leadership team to find out more bugs. After internal testing we release a public beta where we give the update to a limited group of public users and then collect there feedback.
So, it's quite a rigorous process of testing. However, sometimes updates can gives teething issues as successful updates depends on number of factors, like:
- Server configuration: Whether or not server is running the recommended configurations that WordPress community has listed. Outdated version of PHP is the most common reason. Here is the link. https://wordpress.org/about/requirements/
- WordPress version: We have seen customers using quite an old version of WordPress and that cause compatibility issues.
- Plugins: If a site is using outdated plugin or if that plugin is not keeping pace with the industry development standards then it may cause issues.
- Cache plugins: Most of the times we see that cache is no cleared and because of that cached resources are getting rendered thereby causing problems.
- Updating from old version of X Theme or Pro: If you a customer is updating from a very old version of X Theme, then there is a probability of conflicts.
However, we do maintain a stability release that customers can use to rollback the website. You can find the same in your members area. Here is a screenshot.
I am really sorry for the trouble you faced. In case problem is still there, I request you to please create a new ticket and share the details in the same. I assure you that someone from support team will help you out.