How to implement a simple 404 Page to popup when url not found?

Is there a good way to do this without the need to use a plugin? My question is not about its design, only about how to make that working

If one is using the template creation feature from the admin design tab - > Website Editor, one can select 404 and create a respective template (not available within the Cwicly Themer obviously).

got it, but needs to bypass the Themer as mentioned above

Hi @FZwo,

As you mention, you can use a default template for the 404 page.
However, the Cwicly Themer does also provide this possibility for a custom template → Singular → 404

not sure, can’t find that kind of flow within the themer (there is only template → create custom template, and that’s it.

And how to redirect to that 404 page then?

furthermore, working with the FSE 404 Standard, I am not able to select it as template in a 404 page I created (I did not restrict the 404 template to anything)

You don’t need to redirect to it, Wordpress automatically does this for you.

As @Louis mentioned, there are these visibility conditions:

There is no redirection, if I enter an invalid URL, probably there is any general setting on my side

I exactly entered this condition (for the standard fse 404 template I created), but I am not able to select it in a page as template

You don’t actually get redirected to any page.

If you go to domain.com/fakepage, that’s the page that will be loaded, but instead of being blank, it’ll show the 404 template if set up as @StrangeTech was showing above.

EDIT: I would also suggest setting the priority to 999.

First: adding a 404 the standard FSE way does not work, as a template created that way could not be assigned to any page

Second: adding a custom template via the themer, putting the conditions as mentioned above, then it is possible to assign that to a page as a template, but that page content does not display. If instead it is necessary to just put the “oops not found text” to that new template directly, this does not appear when one enters a “fake” URL

There is no assigning it to a page - as it’s for pages that don’t exist.

If you set it as the conditions above, set a priority higher than your regular page template, and visit a URL on your site that does not exist - then the content of that 404 template will show up.

(You need to add “Oops not found” content to your 404 template, in case that’s the part you’re missing).

Yeah, got it, there where 2 ways to implement it: First, use the standard FSE 404 Termplate, and put your content directly into it (what I did now), and second, to set up a custom 404 via the Themer, and assign that as a template to a page, that is then to be designed as the 404 content, that was what me confused a bit (and even more then one is trying to do check that in parallel)