A completely white page, with no message at all, almost always means PHP stopped with an error and the server is set not to show errors to visitors (which is the right setting). WordPress normally catches this and shows "There has been a critical error on this website"; you get plain white when the error happens before WordPress can step in, when that safety net is switched off, or when a cache stored the blank page. Your posts, pages and orders are still in the database. Below is a rebuilt example (not a real client), then the safe order of steps.
/wp-admin, or one page? Everything white points at a plugin, the theme or PHP itself. Only the dashboard usually means one plugin. A single page usually means a page-builder block or a shortcode on that page.functions.php, or the host moving the site to a newer PHP version. The cause is almost always the last change.wp-config.php and, above the line that says "That's all, stop editing", add define('WP_DEBUG', true);, define('WP_DEBUG_LOG', true); and define('WP_DEBUG_DISPLAY', false);. Load the white page once, then open wp-content/debug.log. The last "PHP Fatal error" line names the file, and the folder in its path names the plugin or theme.wp-content/plugins (add -off). WordPress switches it off and keeps its settings. If you cannot tell which one, rename the whole plugins folder, log in, rename it back, then switch plugins on one at a time until the white page returns.functions.php after an edit), undo the edit from your backup, or rename the active theme's folder in wp-content/themes so WordPress falls back to a default theme such as Twenty Twenty-Five. That only works if a default theme is still installed.define('WP_MEMORY_LIMIT', '256M'); to wp-config.php, and if that does not hold, ask the host to raise the PHP memory limit. Then find what is using it, usually one heavy plugin.WP_DEBUG back to false and delete wp-content/debug.log. That file sits at a public address and can show your folder layout to anyone who asks for it.| What you find | What it means | Usual fix |
|---|---|---|
Log names a file in wp-content/plugins/... | That plugin crashed, often right after an update | Rename its folder, then update, replace or roll it back |
Log names the theme's functions.php | An edit or a snippet broke the theme | Undo the edit from a backup; use a child theme or a snippets plugin next time |
| "Allowed memory size of ... bytes exhausted" | PHP ran out of memory | Raise WP_MEMORY_LIMIT or the host's limit; find the heavy plugin |
| Started when the host moved to a newer PHP | Old code that the new PHP refuses to run | Update or replace the plugin or theme the log names |
| Only the dashboard is white | A plugin that runs only in the admin area | Rename plugin folders one at a time until it returns |
| Only you see white; a private window shows the site | A cache kept the blank page | Clear the browser cache, purge the caching plugin and CDN |
WP_DEBUG_DISPLAY on for visitors. Error text on the page can show file paths and plugin versions to people looking for a way in.functions.php from the dashboard's theme editor on a live site. One missing bracket is enough to make the whole site white, and the editor cannot be reached to undo it.If you can reach the host's file manager and the error log, the steps above are usually enough. If the site earns you money every hour it is blank, that is what the box below is for. Related: "There has been a critical error on this website" is the same kind of crash with WordPress's message on it.