Unknown sticky Problem after MySQL upgrade few weeks ago we upgraded mysql server from 5.5 to 5.6
on 1st server few days ago (5May) I reboot mysql server , after this customer reported that some database data table not load to their site . (mostly phpfox - also few in other scripts) - also new data not submitted to database
I was reinstall mysql - disable cloudlinux - cagefs ... but problem not resolve. also rebuild php
after above , I move that database to remote-mysql-test-server with same Mysql version (5.6) and problem resolved. So I found this problem mysql related
yesterday in an other server like above (server B - that mysql upgraded from 5.5 - 5.6 few weeks ago) when mysql server restart , same problem occurred . for example when I answer ticket (WHMCS) , this date not submitted to ticket ... some clients can't update their site .


few website error like this :
SQL] [1364] Field 'stat_time' doesn't have a default value
STRING: INSERT INTO pn_statistics (stat_name,stat_value) VALUES ('Day-1394-02-24','0')

also in this server when I move database to remote-mysql-test-server this problem resolved.


I speak with few system admin and they can't find my issue .


Any suggestion ?
PROBLEM
I think your problem stems from a change in sql_mode.

sql_mode is blank in MySQL 5.5
It is not blank in MySQL 5.6

SOLUTION
Run this command
SET GLOBAL sql_mode = '';

Then, add this to my.cnf to keep sql_mode blank should you restart mysqld
[mysqld]
sql_mode = ''

You do not need to restart mysqld since you set it globally
GIVE IT A TRY !!!