ms_not_installed returns 200

[spacedmonkey]

The ms_not_installed function returns apache state 200. It should return 500. Also there should been an action / filter to modify behaviour within this code.

[jeremyfelt]

In [14317], we moved from die(), which returns 200, to wp_die(), which returns 500 by default - but only in admin views. I'm not sure if there's a good reason to stick with die().

If we did switch to wp_die(), then a filter is available for wp_die_handler to customize that message.

We could also consider an action in ms_not_installed().

[nacin]

We should probably follow whatever dead_db() does. It's possible that dead_db() can be updated to take an arbitrary WP_Error|string as a first argument, defaulting to $wpdb->error otherwise (which is also WP_Error|string). If dead_db() is calling wp_die() early then we should be able to also.

[spacedmonkey]

I thought it would be better to just call dead_db function from ms_not_installed. It means less code and translation to maintain.

[soulseekah]

Seems it's possible to replace the die with wp_die inside that function, no? Just wp_die( $msg, $title );. dead_db is a bit messy and should probably be itself calling wp_die.

[SergeyBiryukov]

#30680 was marked as a duplicate.

[Craig Ralston]

Replaces die() with wp_die() in ms_not_installed()

[Craig Ralston]

If I'm not mistaken, this is as simple as updating to use wp_die() in ms_not_installed().
Note: dead_db() also calls wp_die().

Adding an action to ms_not_installed() is also a good idea but probably should be in a separate ticket, I imagine.

[jeremyfelt]

I think we should go with calling dead_db() instead. It provides the ability to show a custom db-error.php page and handles the 500 error exactly the same as ms_not_installed() would otherwise.

We can also take a cue from is_blog_installed() and set a custom $wpdb->error so that a db-error.php template can act accordingly. Everything we currently store in $msg could be passed this way and ms_not_installed() can just use dead_db(). A more generic message that doesn't rely on a DB query can be used when not in is_admin().

[Craig Ralston]

use dead_db() with custom $wpdb->error if admin

[jeremyfelt]

In 31657:

Return HTTP status code 500 by default in ms_not_installed()

In admin views, specify a response code of 500 when using wp_die() to show an expanded message for a broken or missing multisite installation.

On front end views, use dead_db() rather than die() to generate the generic "Error establishing a database connection" message. dead_db() sets a status code of 500 by default and allows for the override of this generic error with a db-error.php template.

Props craig-ralston, jeremyfelt.

Fixes #30002.