Error during installation at step 1 - Undefined index: host

[grapestain]

It is another instance of this one: #34164

If the environment is set up to report all errors, line 1075 of wp-includes/l10n.php creates an E_NOTICE with Undefined index: host message.

Reason:
At the time of installation the $site_url array does not yet have a 'host' key, so $site_url['host'] is undefined.

You can see here:
https://core.trac.wordpress.org/browser/trunk/src/wp-includes/l10n.php#L1075
} elseif ( ! isset( $src_url['host'] ) || $src_url['host'] === $site_url['host'] ) {

A proper condition would look like:
} elseif ( ! isset( $src_url['host'] ) || ( isset($site_url['host']) && $src_url['host'] === $site_url['host'] ) ) {

[SergeyBiryukov]

Hi there, welcome back to WordPress Trac!

Thanks for the report, we're already tracking this issue in #49145.