Title: Fatal error: Class ‘WP_Theme_JSON_Schema’ Last modified: January 20, 2023 --- # Fatal error: Class ‘WP_Theme_JSON_Schema’ * Resolved [mcgeneraluser](https://wordpress.org/support/users/mcgeneraluser/) * (@mcgeneraluser) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/) * Hi, My website is showing the error message even though the theme is changed in the backend through PHPMyAdmin, Unable to figure out the issue with this, coming under the wp-includes folder * **Fatal error**: Class ‘WP_Theme_JSON_Schema’ * **/home/XXXXXXXXXXXXX/public_html/wp-includes/class-wp-theme-json.php** on line** 403** * There has been a critical error on this website. Viewing 6 replies - 1 through 6 (of 6 total) * Moderator [James Huff](https://wordpress.org/support/users/macmanx/) * (@macmanx) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16394011) * Try [manually resetting your plugins](https://wordpress.org/support/article/faq-troubleshooting/#how-to-deactivate-all-plugins-when-not-able-to-access-the-administrative-menus)( no Dashboard access required). If that resolves the issue, reactivate each one individually until you find the cause. * If that does not resolve the issue, access your server via [SFTP or FTP](https://wordpress.org/support/article/ftp-clients/), or a file manager in your hosting account’s control panel (consult your hosting provider’s documentation for specifics on these), navigate to /wp-content/themes/ and rename the directory of your currently active theme. Hopefully, this will force the default theme to activate and rule out a theme-specific issue (theme functions can interfere like plugins). * Thread Starter [mcgeneraluser](https://wordpress.org/support/users/mcgeneraluser/) * (@mcgeneraluser) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16398766) * Thank you [@macmanx](https://wordpress.org/support/users/macmanx/) for responding, appreciate it. * However we still find our site landing in the same error again and again even after following your instructions, I have added the issue below as an image and also pasted line 403 of **public_html/wp-includes/class-wp-theme-json.php** 👇 * This is the code on line 403 * $this->theme_json = WP_Theme_JSON_Schema::migrate( $theme_json ); * Is this correct syntax wise or any changes needed ? * We have followed your previous steps as responded by you [@macmanx](https://wordpress.org/support/users/macmanx/), but the issue still persists, please look into this code once and let know any changes might be needed * Moderator [James Huff](https://wordpress.org/support/users/macmanx/) * (@macmanx) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16401010) * That’s definitely not what line 403 should be: [https://core.trac.wordpress.org/browser/tags/6.1.1/src/wp-includes/class-wp-theme-json.php#L403](https://core.trac.wordpress.org/browser/tags/6.1.1/src/wp-includes/class-wp-theme-json.php#L403) * Try [downloading WordPress](https://wordpress.org/download/) again, access your server via [SFTP or FTP](https://wordpress.org/support/article/ftp-clients/), or a file manager in your hosting account’s control panel (consult your hosting provider’s documentation for specifics on these), and delete then replace your copies of everything on the server **except** the wp-config.php file and the / wp-content/ directory with fresh copies from the download. This will effectively replace all of your core files without damaging your content and settings. * If you’d like to manually make a backup of your site first, please follow the steps at [https://wordpress.org/support/article/wordpress-backups/](https://wordpress.org/support/article/wordpress-backups/) * Some uploaders tend to be unreliable when overwriting files, so don’t forget to delete the original files before replacing them. * Thread Starter [mcgeneraluser](https://wordpress.org/support/users/mcgeneraluser/) * (@mcgeneraluser) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16407758) * Hello [@macmanx](https://wordpress.org/support/users/macmanx/) , **Thanks a ton** for your instructions, we now have our website back !! Also I would like to have a look at these (below) where another website of ours is throwing same errors as below, please review and let know if it’s solvable like the former one or any other method should be followed. * please find the error message here: [https://prnt.sc/WCvuYP5WUEWQ](https://prnt.sc/WCvuYP5WUEWQ) * **Fatal error**: Call to undefined method WP_Theme::is_block_theme() in **/home/ qxp3cy0l688w/public_html/bbs1001/wp-includes/theme.php** on line **4165** * **Notice**: is_embed was called **incorrectly**. Conditional query tags do not work before the query is run. Before then, they always return false. Please see [Debugging in WordPress](https://wordpress.org/support/article/debugging-in-wordpress/) for more information. (This message was added in version 3.1.0.) in **/home/qxp3cy0l688w/ public_html/bbs1001/wp-includes/functions.php** on line **5769** * **Notice**: is_search was called **incorrectly**. Conditional query tags do not work before the query is run. Before then, they always return false. Please see [Debugging in WordPress](https://wordpress.org/support/article/debugging-in-wordpress/) for more information. (This message was added in version 3.1.0.) in **/home/qxp3cy0l688w/ public_html/bbs1001/wp-includes/functions.php** on line **5769** * There has been a critical error on this website. * As we have only 2 problematic sites under this hosting plan, it would be helpful for us as we get our content published on it back to us. Thanks in Advance. * Moderator [James Huff](https://wordpress.org/support/users/macmanx/) * (@macmanx) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16408378) * I’d do the same process. Start with my first reply, resetting plugins/theme, and if that doesn’t work, do the re-install. * Thread Starter [mcgeneraluser](https://wordpress.org/support/users/mcgeneraluser/) * (@mcgeneraluser) * [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16416495) * Thank you James Huff [@macmanx](https://wordpress.org/support/users/macmanx/), Both our sites are now working good now. Appreciate your help !! Viewing 6 replies - 1 through 6 (of 6 total) The topic ‘Fatal error: Class ‘WP_Theme_JSON_Schema’’ is closed to new replies. ## Tags * [functions](https://wordpress.org/support/topic-tag/functions/) * [json](https://wordpress.org/support/topic-tag/json/) * [wordpress core](https://wordpress.org/support/topic-tag/wordpress-core/) * [wp-includes](https://wordpress.org/support/topic-tag/wp-includes/) * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/) * 6 replies * 2 participants * Last reply from: [mcgeneraluser](https://wordpress.org/support/users/mcgeneraluser/) * Last activity: [3 years, 4 months ago](https://wordpress.org/support/topic/fatal-error-class-wp_theme_json_schema/#post-16416495) * Status: resolved ## Topics ### Topics with no replies ### Non-support topics ### Resolved topics ### Unresolved topics ### All topics