“Critical Error” when I want to customize theme

Sorry to hear you are having an issue. Can you tell me if you are on the latest version of Flat Blocks which is now 1.3.9? WordPress v6.3 had some really extensive changes, especially in the Site Editor and I fixed issues as I ran into them with quick updates to the theme. v1.3.9 should be stable.

If you are still experiencing the issue on v1.3.9 can you please turn on debugging on your site and copy in the more detailed error here (set WP_DEBUG to true in wp-config.php)?

I just updated to v1.3.10 but still not working. Here’s a copy of the debug.log:

[20-Sep-2023 11:06:32 UTC] PHP Fatal error: Uncaught Error: Call to undefined function wp_get_current_user() in /home/www/cooldocstuff/wp-includes/capabilities.php:877
Stack trace: 0 /home/www/cooldocstuff/wp-includes/theme-previews.php(17): current_user_can(‘switch_themes’) 1 /home/www/cooldocstuff/wp-includes/class-wp-hook.php(310): wp_get_theme_preview_path(‘envo-shopper’) 2 /home/www/cooldocstuff/wp-includes/plugin.php(205): WP_Hook->apply_filters(‘envo-shopper’, Array) 3 /home/www/cooldocstuff/wp-includes/theme.php(317): apply_filters(‘template’, ‘envo-shopper’) 4 /home/www/cooldocstuff/wp-includes/theme.php(328): get_template() 5 /home/www/cooldocstuff/wp-includes/l10n.php(1306): get_template_directory() 6 /home/www/cooldocstuff/wp-includes/l10n.php(1331): _load_textdomain_just_in_time(‘ali2woo’) 7 /home/www/cooldocstuff/wp-includes/l10n.php(185): get_translations_for_domain(‘ali2woo’) 8 /home/www/cooldocstuff/wp-admin/includes/plugin.php(160): translate(‘Aliexpress Drop…’, ‘ali2woo’) 9 /home/www/cooldocstuff/wp-admin/includes/plugin. in /home/www/cooldocstuff/wp-includes/capabilities.php on line 877

[20-Sep-2023 11:06:32 UTC] PHP Notice: Die Funktion is_embed wurde fehlerhaft aufgerufen. Bedingte Abfragen (Conditional Tags) funktionieren nicht, wenn die Beitrags-Abfrage (query_posts) noch nicht durchgeführt wurde. Sie geben dann immer ?false‘ zurück. Weitere Informationen: Debugging in WordPress (engl.). (Diese Meldung wurde in Version 3.1.0 hinzugefügt.) in /home/www/cooldocstuff/wp-includes/functions.php on line 5905
[20-Sep-2023 11:06:32 UTC] PHP Notice: Die Funktion is_search wurde fehlerhaft aufgerufen. Bedingte Abfragen (Conditional Tags) funktionieren nicht, wenn die Beitrags-Abfrage (query_posts) noch nicht durchgeführt wurde. Sie geben dann immer ?false‘ zurück. Weitere Informationen: Debugging in WordPress (engl.). (Diese Meldung wurde in Version 3.1.0 hinzugefügt.) in /home/www/cooldocstuff/wp-includes/functions.php on line 5905
[20-Sep-2023 11:06:34 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:34 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:35 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:37 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:38 UTC] PHP Notice: Die Funktion register_rest_route wurde fehlerhaft aufgerufen. Das REST-API $args sollte ein Array von Arrays sein. Ein abweichender Wert wurde für legalweb/v1/lwTextEndpoint festgestellt. Weitere Informationen: Debugging in WordPress (engl.). (Diese Meldung wurde in Version 6.1.0 hinzugefügt.) in /home/www/cooldocstuff/wp-includes/functions.php on line 5905
[20-Sep-2023 11:06:39 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:40 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:41 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:43 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:43 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:44 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24
[20-Sep-2023 11:06:46 UTC] PHP Deprecated: The PSR-0 Requests_... class names in the Requests library are deprecated. Switch to the PSR-4 WpOrg\Requests\... class names at your earliest convenience. in /home/www/cooldocstuff/wp-includes/class-requests.php on line 24

That is a very strange error. That is core WordPress itself crashing. It’s trying to load your user profile to see if you have the ability to preview a theme and it’s crashing on its own call to wp_get_current_user().

The theme doesn’t ever call that function and this crash is before it even shows the theme. I.e. WordPress can’t determine if you are allowed to preview a theme.

Can you preview other themes? Both core WordPress TwentyTwentyThree and other themes downloaded from www.ads-software.com?

I get the same error with the “twenty twenty three” and “twenty two” theme but not with other themes. “Twenty one” works as well as other third party themes. When I activate the flat blocks theme it works. I can then enter the customizer (wich looks totally different from what I am used to), I can tweak the appearance. But only when it’s live.

Interesting, so it seems that block-based themes are all experiencing the crash, while older non-block-based themes aren’t. This theme and TwentyTwentyThree are completely block-based, also referred to sometimes as “Full Site Editing”.

I for sure can’t get an error like this to come up with any themes on any of my websites running all of my various themes. I’m going to go ahead and mark this as “resolved” (not a theme issue), but will continue to monitor it and respond here.