Error with replication from mysql 5.5 to 5.6 (no replies)

Hi
I have to migrate a mysql configuration with 5.5 server in replication master -> slave (2 slave) to mysql 5.6
To do this, I've tired to add a mysql server 5.6 with a backup of database loaded, to the replication to sync with the master.
But when I try to start slave, the new server do not sync with master and print this message in the error log:

2015-03-24 09:51:37 2820 [ERROR] Error reading packet from server: Out of memory (Needed 538976296 bytes) ( server_errno=5)
2015-03-24 09:51:37 2820 [Note] Slave I/O thread: Failed reading log event, reconnecting to retry, log 'S01MYSQL-bin.000505' at position 870601394
2015-03-24 09:51:37 2820 [Warning] Storing MySQL user name or password information in the master info repository is not secure and is therefore not recommended. Please consider using the USER and PASSWORD connection options for START SLAVE; see the 'START SLAVE Syntax' in the MySQL Manual for more information.
2015-03-24 09:51:38 2820 [Warning] Slave I/O: Notifying master by SET @master_binlog_checksum= @@global.binlog_checksum failed with error: Unknown system variable 'binlog_checksum', Error_code: 1193
2015-03-24 09:51:38 2820 [Warning] Slave I/O: Unknown system variable 'SERVER_UUID' on master. A probable cause is that the variable is not supported on the master (version: 5.5.28-log), even though it is on the slave (version: 5.6.23-log), Error_code: 1193

I've checked the server ids, they are unique. Memory and disk space are free. Any ideas abount to solve this problem?
Addition: on the envoirment there is the semi-sync replication active. I've activated also this on the new master, but the problem persist.