You have 2 options.

1. Update to c5.6.4 latest from the legacy github, which supports php7. This would be a safe option if the content of your site is mature and you don't require a redesign. If your site depends on many addons that are not available for 8.5.4, that would be another reason to stop here.

2. Update stops at 5.6.4. Beyond that is not compatible. To use the latest v8.5.4 would involve creating a new site on a fresh v8.5.4 install. Possibly migrating some of your content from the old site using the official content migration tool or my Universal Content Importer. Or if there are not too many pages, its easiest to simply copy and paste the content.

As your site is currently broken, either of the above would need to create a clone of the site on a dev system to work with, then once complete upload the fixed, updated or new site to your host.

If you want someone to repair your site and update it to 5.6.4.0 as a paid job, send me a private message.

Thanks for the offer. I'll bear it in mind. My gut feeling is that if I were to pay someone, I think it would have to be to get up to latest version.

Thanks for the response. I am thinking about the option to install latest and rebuild the content. As you say, it's not many pages and I have been able to capture all the existing content so...

Not 100% on where to go next, but be sure, I'll ask here if I get stuck.

Thanks for the response. I am thinking about the option to install latest and rebuild the content. As you say, it's not many pages and I have been able to capture all the existing content so...

Not 100% on where to go next, but be sure, I'll ask here if I get stuck.

I've read that one has to go step-by-step from one version to the next. Is it possible to upgrade directly from 5.4.1.1. to 5.6.4?

If you look at the release notes, there are certain key versions you need to step through. You don't need to go through every single version.

Usually with that type of upgrade I would go

5.4.1.1 -> 5.4.2.2
5.4.2.2 -> 5.5.0
5.5.0 -> 5.6.0
5.6.0 -> 5.6.3
5.6.3 -> 5.6.4

All of these steps might not be necessary but that's what has worked for me in the past

@hutman Thanks for the insight. I've tried 5.4.1.1 to 5.4.2.2 already and it failed on me. I had to restore from a backup. I'm considering a clean reinstall at 8.5.

Updates can typically fail on:
- Writability of update directory (check directory permissions)
- Timeout (force update repeat a few times can help)
- Incompatibility of packages (update all addons & theme first)
- /application code (so many routes to doom)
- Incompatibility of theme css (unlikely to cause a complete fail, but could result in style bleed)
- Attributes (the complexity of attribute data and lack of garbage collection sometimes leads to skewed data when an update modifies attribute data)

Hence experienced developers would usually make a clone of your site at 5.4.1 on a dev system where they have greater control of all these factors, run all the updates there and generally clean things up, then replace the live site with a clone of the updated and cleaned dev site.

If you don't have many pages, starting fresh in 8.5.latest may be a good move. A site as old as yours will be carrying a lot of excess baggage and core updates create more excess baggage. Its like a house you have lived in for years, where the garage, loft and cellar are filled with stuff put aside and long forgotten. Except with a web site you need technical expertise to even work out what is hidden where and whether it is still needed. So a clean start dodges the entire excess baggage issue.

However, a fresh start also depends on availability of any addons you use, or their equivalent, and updating /application code.