Need a pro opinion about the downside of updates

updating plugins or themes while the site already contains content, can be shaky

Not updating plugins and themes can be even worse. Any one of those updates could be a security patch. Not updating might allow a hacker to access your site and a hacked sites takes weeks to sort out. Always keep everything up to date.

If you want to test out updates, try installing WordPress locally with some dummy content and then test your updated themes and/or plugins there.

I didn’t mean that I rather not update

Ah – sorry. I mis-understood.

I asked about the potential benefits of building up the site from scratch with the updated versions.

I don’t see any real benefits myself. What would you expect to achieve or avoid?

installing the latest version of something for the first time is less prone to errors than updating to the latest version from an old version

I’m not sure that updating software locally is analogous to updating a web app on a remote server. If you really want to be ultra careful about updating, you might want to look at updating manually – especially WordPress core. As with any automated system, there’s always going to be a small percentage error due to problems in inter-server communications compared to using FTP yourself.

But I genuinely don’t see any advantage to re-building the site every time there’s a major update. I’ve been using WP for over 10 years- both for myself & professionally – across many sites with many different hosts – and I don’t think that this idea has ever occurred to me.

The only time I have started from scratch has been when a client’s site was so old that a rebuild was more practical than multiple smaller updates and the potential problems of out-of-date plugins. But never when updating from (say) 3.8 to 3.9. If you always ensure that you carry out a db backup before any upgrade, then – should the absolute worst happen – a rebuild is relatively easy.

My comments about creating a local or testing copy of WordPress are still valid, though. Many people do like being able to test for potential problems before risking the live site – especially if they are running a lot of plugins.

that makes you comfortable hit that ‘update’ button

Experience, I suppose, Updating WordPress hundreds of times. 🙂

Whether it only changes files or is does it mess with the db as well.

It depends upon the update. Minor WP core upgrades often only involve some file updates. Major core updates often involve a database update as well.

With plugins, it’s not possible to give a general answer as it is so very dependant upon the plugin involved and what has been changed. Not all plugins write to the database as they focus on making content changes on the fly. These are unlikely to touch the database during their upgrade. Those that have their own db tables and/or saved options may touch the db during an update.

Themes generally never touch the db during their updates. That said, the db on a semi-decent hosts is often the most efficient and the fastest part of any WP site. So db updates are usually problem-free. Db backups are made as insurance against the one-in-a-million time when something does go badly wrong.

Most of the issues that arise out of an update are due to incompatibilities between any permutation of WP core, theme and plugins. These can usually be fixed quickly by renaming the current theme’s folder (this activating the default theme) and/or resetting the plugins folder. This is where a local/test install comes into play as it allows you to check for such problems before touching the live site.

Generally speaking though- and considering how many millions of sites go through the process every time WP updates – the amount of reported update problems is very small. Probably 1% or less. So don’t get too hung up on the potential dangers of upgrading. As long as you have a good db backup, everything else is fixable. 🙂

what happens to things I already configured?

I think that depends upon the theme, so it’s a question you would need to ask the theme’s developer. Personally, whilst I have added new features as part of a theme update, I’ve never removed any existing ones if at all possible as I appreciate that many users may rely on them.

If suddenly the developer will decide those should be removed, I might get some errors of some sort, no?

In theory, no. The updated theme should remove all calls to those old features. So, although your site might be missing something that was shown previously, it should never collapse or display any errors. At worst, you might be left with an extra, unneeded row in your wp_options table but that’s about it.

If you’ve developed your own child theme and are using some theme-specific feature, then I would always suggest that you place that call inside a conditional such as:

if( function_exists( 'theme_function' ) ):
[do stuff]
endif;

or

if( isset ($theme_options['option_name']) && $theme_options['option_name'] == 'foobar' ) :
[do stuff]
endif;

That way, you should be protected from the child theme falling over because theme_function() or option_name aren’t in the updated parent theme. Custom fields will still exist but they just wouldn’t be used any more.

Generally speaking, I think that the more you tinker with themes (and perhaps even have a go at writing a simple plugin), the more confident you become that – whatever happens – it’s all fixable.

You will get there. We all started knowing nothing about WordPress.

And I’m glad I could help. It’s been an interesting discussion. 🙂