Sounds like a good idea to me. I would not change the existing string but add a new message to 3.10 on "upgrades to the next major" updates only.
As 3.10-> 3.10 and 4.1->4.1 updates are not affected by this.

It is a issue of J3 and I suggest replacing

The Joomla 4.x update

Upgrading J3 to J4 can be a big step, ....

Thx!

Updated solution:

Warning
Upgrading J3 to J4 can be a big step, depending on the complexity of the website.
It is highly recommended that you do not perform this step on the live site but in a test environment.
A copy of the live site can be set up very easily using a backup/restore extension (linked to /administrator/index.php?option=com_installer&view=install#web).

..only in case of a major upgrade.

@brianteeman May you please comment your thumb down?

My bank balance increases from broken live sites but the users involved in those accidents are not happy - so I think it is important to make things clearer for non-experts.

Better to spend the time improving the update process and mediate many of the known issues than to scare people away from ever updating

OK, good points.

I see that as an improvement of the update process.
Nobody with extended knowledge does that major update on the live site, because there is always some manual work to do.

The reason for my suggestion: Many people contact me in my (half-commercial) J! troubleshooting chat over the last few weeks because they crashed their live sites and don't even know how to successfully restore a backup.

That scares more imho and greenhorn's frustration regarding J4 live crashes could be minimized in that way.

Hello community,

there also should be a "pre-update-check" that checks for the richt filesystem permissions and a "post-update-check" that checks if all files have been installed correctly.

best regards,
Daniel

If the update fails, the post-update-check will not work ;-)
@ #37110

The Pre-Update Warning should really be improved.

It's all documented already in a very attractive way in multiple languages, including Development Location and Akeeba Backup recommendation:
https://docs.joomla.org/Joomla_3.x_to_4.x_Step_by_Step_Migration

But users do not read/google the f****** manual beforehand to be prepared, so it should be part of the warnings straight away in backend, to protect unexperienced users from doing something wrong - make it almost impossible that they act around the already existing 5-? documentation from official site.

Kind regards
Pascal

Thank you for raising this issue.

Joomla 3 is now in security only mode with no further bug fixes or new features.

As this issue doesn't relate to Joomla 4 it will now been closed.

If we are mistaken and this does apply to Joomla 4 please open a new issue (and reference this one if you wish) with updated details for testing in Joomla 4.
cc @zero-24