Firstly check your apache
error log, If you are getting the following error:
=====================================
[Thu Feb 04 22:08:36 2016] [error] [client 116.202.181.214]
ModSecurity: Output filter: Response body too large (over limit of 524288,
total not specified). [hostname "example.sg"] [uri
"/wp-admin/post-new.php"] [unique_id
"VrNbY7Tw6W0AAEf@BuYAAAAD"]
[Thu Feb 04 22:08:44 2016] [error] [client 116.202.181.214]
ModSecurity: Output filter: Response body too large (over limit of 524288,
total not specified). [hostname "example.sg"] [uri
"/wp-admin/post-new.php"] [unique_id
"VrNba7Tw6W0AAEhuMh0AAAAI"]
=====================================
It was due the ModSecurity over limit, So we have to increase the limit of that domain.
Go to your server Apache configuration file
vi /usr/local/apache/conf/httpd.conf
find the domain’s virtual host entry
Add the following lines inside virtualhost entry
<VirtualHost Domainname/IP>
<IfModule mod_security2.c>
SecResponseBodyLimit 549658718
</IfModule>
</VirtualHost>
Save and exit, It will fix the issue....
