slave error

Percona 5.6.15

The slave suddenly stop working. get the below error:

Slave I/O: Got fatal error 1236 from master when reading data from binary log: ‘The slave is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master has purged binary logs containing GTIDs that the slave requires.’, Error_code: 1236

Checked the master , all binary log files are there.

How it happen? and how to fixed it