session_write_close(): Failed to write session data using user defined save handler

Hello,

I want to allow concurrent requests from a client for simultaneous AJAX calls. 
In each php function called, I start my code with session_write_close() to unlock the session. But I randomly get this message : 

Code:

session_write_close(): Failed to write session data using user defined save handler.

I'm using redis and everything work fine. Just getting this message sometimes in my logs.

Any idea?
Cheers

Read the user comments here:

PHP.net - session_write_close

It seems that the output buffering is causing session problems on php 7+

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )

Oh, nice catch ! I will try to disable it and see what happend 
Thanks for your answer

Read the user comments here:

PHP.net - session_write_close

It seems that the output buffering is causing session problems on php 7+

Well, I set output buffering = off in php.ini but it doesn't solve the problem. I still get "Failed to write session data using user defined save handler" randomly.

I find this thread on stackoverflow : https://stackoverflow.com/questions/3411...ssion-data
Not sure if the selected answer can apply to codeigniter ? I'm using Redis.