Alert Log File Errors in Oracle 11g R2

1. Error:
kewastUnPackStats(): bad magic 1 (0x2b2b8f4652ad, 0)

Solution:
ALTER SYSTEM SET control_management_pack_access='NONE' SCOPE=MEMORY;
and Apply patch the patch 8730312

2. Error: Checkpoint not complete in alert log file Oracle 11gR2
Reason: your online redo logs are defined too small to handle the load and you have filled and need to switch to a new online redo log before the checkpoint triggered by the previous log switch has been completed.
Solution:alter system set archive_lag_target=0 scope=both;
and increase the log file size

Alter database add logfile group 4 'c:\oracle\oradata\testdb\redo04.log'
size 250M reuse;
Alter database add logfile group 5 'c:\oracle\oradata\testdb\redo05.log'
size 250M reuse;

Now switch log file 2 times to make these new files online.

Alter system switch logfile;
Alter system switch logfile;

force checkpoint to write all contents to data files.

Alter system checkpoint;

Drop the old log files.
Alter database drop logfile group 1;
Alter database drop logfile group 2;
Alter database drop logfile group 3;