Saving didnt work! Please reload the page and try again

Hi Admin

I have trouble when updating web logo, etc.. give me “Saving didnt work! Please reload the page and try again”

wp-content/uploads permission already change to 777
wp-content/themes permission already change to 755
wp-config.php insert new line define(‘WP_MEMORY_LIMIT’, ‘512M’);

.htaccess
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>