Saving certain site settings (E.g. in Advanced General) breaks/reverts theme

[khristiansnyder]

Summary

On a simple and AT sites, when any setting is changed in Advanced General, the theme breaks and completely reverts to a different theme or just shows broken/blank homepage for the site. I tested with Karuna and Twenty Twentyone active and after saving some new sittings in Advanced General, my test site switched to Twenty Fifteen.
WP-Admin/themes shows an error: The active theme is broken. Reverting to the default theme.

Steps to reproduce the behavior

1. On a simple or AT site, make sure one of our internal themes is activated (such as Twenty Twentyone) and then save any setting in Settings ➤ Advanced General
2. After saving the settings, the theme is broken and reverts to a different theme. For example, I had Twenty TwentyOne active, and that was reverted to Twenty Sixteen.
3. WP-Admin ➤ Themes has an error: the active theme is broken. Reverting to the default theme.

Is this specific to the applied theme? Which one?

Seems to happen in both block-based themes and premium themes.

Does this happen on simple or atomic sites or both?

Simple and AT, but so far only tested themes in our internal library

[poojashetty18]

Another report on 30008759-hc
Theme: Verity

The AT site user also made changes to Advanced General settings and changed the New User Default Role from "Customer" to "Vendor"

[cpapazoglou]

I have been looking to the issue, but still don’t have a clue.
It’s unrelated to nav-unification or the menu entry “Advanced General”.

Just a hint: It doesn't reproduce on eCommerce plans.

[cpapazoglou]

validate_current_theme returns false because file_exists( get_stylesheet_directory() . '/style.css' ) is false.

It seems that stylesheet option gets empty when saving the form in wp-admin/options-general.php

[katiebethbrown]

If the stylesheet option is empty, could that also be what's causing the theme_mods_{themeslug} option to get overwritten with -, causing the issues we're seeing saving customizer changes?

#53431

If I'm reading it right (I might not be), JP sync uses the stylesheet option to sync the theme_mods:

https://github.com/Automattic/jetpack/blob/05de5b8f8fba2bd86c607abbc3e98e49c9cc739c/projects/packages/sync/src/modules/class-options.php#L228

[cpapazoglou]

theme_mods_

I am not sure yet if these issues are related. FWIW, saving the form in wp-admin/options-general.php will both empty the stylesheet and theme_mods_{themeslug} as a result of both of them being in the $allowed_options array.

I am now trying to find how they get added there.

[cpapazoglou]

Tested in an Atomic site, disabling Gutenberg plugin resolved the problem...

[cpapazoglou]

I just booted a local Gutenberg 10.7.2 and the problem reproduces clearly over there!

[cpapazoglou]

Here is the offending code
https://github.com/WordPress/gutenberg/blob/27afc4d43f02713fd40f4a35b6f6f8fabc175d0f/lib/rest-api.php#L190-L217

which is already fixed in WordPress/gutenberg#32229

[cpapazoglou]

Related convo about pushing a custom build for Simple sites p1623062896261500-slack-C7YPUHBB2

Atomic Sites will need to wait for the next release of Gutenberg on Wednesday Jun 9.p1623080514158400/1623076293.157800-slack-C45SNKV4Z

[cpapazoglou]

Related convo about restoring the affected sites stylesheet & theme_mods_%
p1623083655133000-slack-C020SHYRB24

[formosattic]

+1 4048860-zd-woothemes

[cpapazoglou]

We have stopped the spread of the issue and we are trying to restore the correct stylesheets to the affected blogs. It will be resolved as part of #53431. Let's continue the discussion there.

[cpapazoglou]

#53431 (comment)