Commit failed due to failure of an earlier commit on which this one depends

Hello,
I am using parallel replication and the table on slave initially was myisam.
inserts are either ignored (and if duplicate key found, I am simply ignoring error 1062 in config) or inserted.
I switched to innodb to check the speed improvements and got the error in subject (error num reported 1964)
Then switched again to myisam.

Recently the app logic been changed and we are using INSERT + ON DUPLICATE KEY UPDATE
so no duplicate ignores any longer and it should work fine.
However, switching to innodb resulted in same error again and now switched back to myisam.

Another thing - alter to myisam for a table 30gb with 2 indexes took about 15 minutes, and to innodb (from myisam) around 2 hours. But I guess that's by design.

All other myisam tables that have simple insert without primary key working fine as innodb, without any errors.

masters have insert delayed which is seen on slave, but I guess slave converts this to simple insert in order to keep same order but maybe this can help as well

Thanks,
Alex