White Screen on wp-admin Only (Front End Loads Fine)

Connect via SFTP/SSH and check wp-content/debug.log and the server/PHP error logs immediately after reproducing the issue. WordPress recommends using WP_DEBUG_LOG to capture errors in debug.log.
If the log identifies a specific plugin, temporarily rename only that plugin’s folder to deactivate it, then test /wp-admin/ again.
If there is no clear error, temporarily rename the plugins folder to something like plugins_old and test the affected admin page. WordPress officially recommends this method when the admin screens cannot be accessed.
If the issue still occurs with all plugins disabled, check the active theme/custom code and PHP/server logs. A theme can also cause a white screen.
If the issue affects all admin pages and the logs don’t indicate a plugin/theme problem, then investigate WordPress core files, PHP version/memory limits, permissions, and server configuration.
Do not rename wp-admin as a first troubleshooting step. Replacing WordPress core files can be considered later if there is evidence of corrupted/missing core files; don’t touch wp-content or wp-config.php during a core replacement.
So your two SOPs can share the same Debug Log → Specific Plugin → All Plugins flow, with additional checks for admin-specific issues.

Symptom

Public site loads normally, but /wp-admin/ is blank or errors - isolates the cause to an admin-only hook/plugin.