Hi @chalangke,
To replicate the error at our end, it will be good if you can provide the stepwise explanation with the screenshots or a video explaining the same.
You can also add the below-given code into your wp-config.php for debug setup,
and send us the error logged into the file name debug.log inside the wp-content folder to check the logged error.
// Enable WP_DEBUG mode
define( 'WP_DEBUG', true );
// Enable Debug logging to the /wp-content/debug.log file
define( 'WP_DEBUG_LOG', true );
// Disable display of errors and warnings
define( 'WP_DEBUG_DISPLAY', false );
//SET PHP INI DISPLAY ERROR FALSE
@ini_set( 'display_errors', 0 );
Please find the video will help you to edit wp-config.php and add the above code: https://www.youtube.com/watch?v=3SDPTafEM8o
Hope it helps.