Something silently (no errors in network) blocks my backend savings

[kindsgar]

I am trying October cms, and i found a strange behavior in saving content from the backend:

it saves files directly on the filesystem (flat file cms) but i noticed that when i save something that has those characters close

> <

without nothing in between the process fails without any warning.

here the response where everything works:

Accept-Ranges:bytes
Age:0
Cache-Control:no-cache
Connection:keep-alive
Content-Length:750
Content-Type:application/json
Date:Sun, 07 Feb 2016 00:59:11 GMT
Set-Cookie:october_session=eyJpdiI6Ijg2Mlp1alQwMWx2WVZGU1ZFam9oOGc9PSIsInZhbHVlIjoidmhBZ3RxVVlpWGxiQ2VIMDM0XC81TldCdjV0UHgrNDZRb2t4ZXN2UUFVMDJ5N0UralJcL0I2bHZOWjF0N2FDMm1hUm1Vdml0MHB0OGU0VzB1QjhkRjY1QT09IiwibWFjIjoiMjY3ODM5OGY3ZmZlMDBiMzEwZWM0ZTFlYWM2ZmE2MmI5ODFhOTdjMWRjNWM5ZDdiNGNiZTAzZWUzZmE1MjE3MiJ9; expires=Sun, 07-Feb-2016 02:59:11 GMT; Max-Age=7200; path=/; httponly
X-Cache:MISS
X-Varnish:189825416

and this is the one when the save fails:

Accept-Ranges:bytes
Age:0
Cache-Control:no-cache
Connection:keep-alive
Content-Encoding:gzip
Content-Type:text/html; charset=UTF-8
Date:Sun, 07 Feb 2016 00:59:49 GMT
Set-Cookie:october_session=eyJpdiI6IitFeGpQbW5MZHlVZkdVUXpkbHdNMmc9PSIsInZhbHVlIjoiQjZcL1orTmNkaTNwTklQdFZsXC9ld250QkhnbTZYNkNTZnI4QmRhUzl4YWlGTWZyWHVLdXBxUmdNb2FWVWNoQzNrYWJDMXNmQnVVejZvSnArVnZxUUtPUT09IiwibWFjIjoiYmIzM2Q1YjhlOWE1YmI0NTM2NTY1MzUzMWRhZDY4ZWQzMjQ3MTIxNjk4ZTRhNzI5Zjk2MWFmYzNkNDBiZDUxZSJ9; expires=Sun, 07-Feb-2016 02:59:50 GMT; Max-Age=7200; path=/; httponly
Transfer-Encoding:chunked
Vary:Accept-Encoding
X-Cache:MISS
X-Varnish:184389152

I cant find any error, then i dont know what's going on and why the process is blocked...

on the github project i found a similar issue, and is from another x10hhosting user (he didnt managed to solve it).