Hi !
I don't know what Cirian advises you but basically you should have done some other things beforehand to do this migration. The template is just one thing.
In case you are unfamiliar with these important steps. Here are some links that can help:

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Links:

1. https://www.joomla.de/joomla/anforderungen
Joomla 4 Dokumentation

2. https://docs.joomla.org/Why_Migrate/de

3. https://docs.joomla.org/Migration_Step_by_Step_Self_Assessment/de

4. https://docs.joomla.org/Planning_for_Migration/de

5. https://docs.joomla.org/Planning_for_Mini-Migration_-_Joomla_3.10.x_to_4.x/de

6. https://docs.joomla.org/Joomla_3.x_to_4.x_Step_by_Step_Migration/de

7. https://docs.joomla.org/Joomla_3.10_to_4.x_Common_Migration_Errors/de

JED Errweiterungen die Joomla 4 ready sind:
• https://extensions.joomla.org/instant-search/?jed_live%5BrefinementList%5D%5Bversions%5D%5B0%5D=40

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MOST IMPORTANT: BACKUP (that you have tested if it works!)

Hi

thank you very much for your kind hints. In fact my request concerns the updating process for the J51 template only. I am very familiar with the updating process of Joomla 3 to Joomla 4.

I tried both methods but either of them was unsuccessful:

Method a)
- Install the J51_Template_J4 over the existing J51_Template_J3 in Joomla 3
- Then start the Joomla Update process

Here I get a «500 behaviour::caption not found» error on any page.

Method b)
- Update Joomla 3 to Joomla 4
- Then install the J51_Template_J4 over the existing J51_Template_J3

Here the home page was ok, but any other page produced a «500» error.

A new installation with the J51_Template_J4 was ok. But here all previous template settings are lost.

So I got the impression, that it is not possible to upgrade from a J51_Template_J3 to J51_Template_J4.
Unless Ciaran has an idea.

Kind regards
Chris

ok !

As far as I know, only the last three templates are capable of Joomla 4 (Nina, emani, Layla)
The others are still to come. so it is described here in the forum and in the templates...

What is your template?

J51_Nina.
On Joomla 3 I had J51_Nina_J3, then I bought J51_Nina_J4.

ok! sorry
then @ciran has to help you

I think I found a solution. It seems to be working. But I am not sure if this is the way that Ciaran would recommend.
I would like to preface saying that I am doing this work with a copy of the live website, not with the live website itself. At least making a backup before beginning is strongly recommended.

- Install J51_TemplateName_J4 in the Joomla 3 version of the website
- Do not be surprised: the frontend will now produce an error message
- Complete any other checks and steps that are necessary before starting the Joomla update
- Update Joomla 3 to Joomla 4
- The frontend will still produce an error message
- Delete any files and folders from /templates/j51_TemplateName/... except a possibly existing custom.css
- Install again J51_TemplateName_J4
- Now the frontend works fine now and the template settings from the Joomla 3 website are respected

The aim of my procedure is to keep the template settings that are stored in the database. And then it seems as if there are some old files somewhere in /templates/j51_TemplateName/... that are not overwritten by installing J51_TemplateName_J4. That's why I deleted the whole path and reinstalled the template. I have had a good experience with it.

Kind regards
Chris

Hi Chris

I would personally suggest installing the Joomla 4 version of the template after you update your installation to Joomla 4 but ultimately it will not make any difference to the end result. One thing I would suggest before updating is to rename your ../template/[YourTemplate]/html/ folder to html-backup. We have seen some issues where this folder is not updating correctly. Renaming the html folder first will resolve this issue and why your described solution most likely works.

Ciaran

I tried this procedure and now my back end area where I control the settings for the styles looks like a mess (see screenshot).

Any ideas how to fix this without losing my styles and settings?

Hello

It appears your template admin is still loading the old CSS. TO amend try doing a full refresh in your browser (CTRL + F5).

Ciaran

What if I have a template that cannot be updated from J3 to J4 but I need to use my domain for the new J4 template? Thanks

Please rephrase this question. I don't really understand what the problem is.

I have privilege that cannot be upgraded. But I also have the other templates that can. I need to develop an entire new template J4 - but my domain name is already with Privilege .. So I know I probably need to back it up but how do I ensure that my domain will be used with the new Template and not the old one. I need to use my domain currently in use

I don't know how to articulate it any better.. bc I don't understand

If your template is no longer compatible with Joomla 4, you must first purchase/install a compatible template and then set it as the "default". Only then will the newly installed template be displayed.

Best regards

thank you..
Maybe I am overthinking the process. I have purchased templates compatible with J4. If I install it and set as default then it will overwrite the domain I am using with privilege correct? I'm not sure there's an understanding. For example I want to keep referring to the info I have with my current privilege domain http://www.*******.com. When I install the new J4 compatible template it will remove all of my content and design from http://www.******.com. I know this shouldn't be difficult and maybe I am over thinking this but its been holding me up. Thanks

You're actually worrying a bit more than necessary – which is perfectly understandable.

In short: No, your existing domain and its content will not be overwritten or deleted simply because you install a J4-compatible template and set it as the default.

In more detail:

A Joomla template only affects the design (frontend/backend), not the domain, the content, or the database.
Your privileged domain (e.g., http://www.*******.com) will remain unchanged and accessible.
Installing a new template does not remove any content (articles, menus, categories, users, etc., remain unaffected).
Setting the new template as the default only changes the website's appearance, not its structure or stored data.
You can switch between templates at any time or revert to the old template as the default.

Important to know:

Some templates include demo data – this is only installed if you actively select it.
A backup before making major changes (e.g., with Akeeba Backup) is always a good idea, just to be on the safe side.

In conclusion:

You can safely install and test the J4-compatible template. Your domain and all its content will remain intact – nothing will be overwritten.

So you're on the right track ?

Oh wow.. OK, here I go .. all I can do is try but I have also implemented a lot of my own code with privilege and using external extensions. So I am going to install Bianca template over a Privilege template. Also my php will not update with J3, so I need to take care of this too. But should I worry if I install J4 over J3 and Joomla now uses J5/J6 ..
Thanks
a