What is Safe mode?
Safe mode is an emergency action that starts WordPress without activating any plugins or themes. It will help you investigate issues or solve errors when there's a failure to boot WordPress.
Starting WordPress in Safe Mode
1. Navigate to [Emergency Action] menu under [Dev] menu on your site
2. Scroll down to the [Safe Mode] section
3. Check the type of Safe mode:
Deactivate all plugins
Deactivate all themes
4. Then click the [Start container in safe mode] button.
5. Log in to WordPress and check that safe mode is working.
Plugins:
No plugins are activated.
Themes:
Default theme is activated (WordPress 4.9's default theme is TwentySeventeen)