MySQL: Adding innodb_log_file_size in my.cnf causes not starting MySQL service I checked and found that InnoDB pluginis active.
By default, Innodb_log_file_size=5MB. As per the MySQL Documentation, 
its ideal values range from 1MB to 1/N-th of the size of the buffer pool, where N is the number of log files in the group.

InnoDB_buffer_pool_size=1024MB and innodb_log_files_in_group=2


So, Value of Innodb_log_file_size should be 512MB.
To achieve this, I have written below line in /etc/my.cnf and tried to restart it.

innodb_log_file_size=512M


I am getting below error:
Starting MySQL.Manager of pid-file quit without updating fi[FAILED]

Please note that I have only two log files -one is for slow query log file and another is error log. 


Can anyone help me to find why there is a strange behavior and I am
not able to edit Innodb_log_file_size?
To change innodb_log_file_size do following


Stop MySQL gracefully. Check the error log and make sure it was "Normal shutdown", no crashes, no errors etc.
Move existing ib_logfile* to safe place. You will need them if you want to roll back
Change innodb_log_file_size in my.cnf to the new value
Start MySQL. InnoDB will notice there are no ib_logfile* and will create new ones