Gather Schema Statistics fails with Ora-20001 errors after 11G database upgrade :

Gather Schema Statistics” program reported following errors in request log files :
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Start of log messages from FND_FILE
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In GATHER_SCHEMA_STATS , schema_name= ALL percent= 10 degree = 8 internal_flag= NOBACKUP
stats on table FND_CP_GSM_IPC_AQTBL is locked
stats on table FND_SOA_JMS_IN is locked
stats on table FND_SOA_JMS_OUT is locked
Error #1: ERROR: While GATHER_TABLE_STATS:
object_name=GL.JE_BE_LINE_TYPE_MAP***ORA-20001: invalid column name or duplicate columns/column groups/expressions in method_opt***
Error #2: ERROR: While GATHER_TABLE_STATS:
object_name=GL.JE_BE_LOGS***ORA-20001: invalid column name or duplicate columns/column groups/expressions in method_opt***
Error #3: ERROR: While GATHER_TABLE_STATS:
object_name=GL.JE_BE_VAT_REP_RULES***ORA-20001: invalid column name or duplicate columns/column groups/expressions in method_opt***
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End of log messages from FND_FILE
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  Action :
To Check which objects or tables are locked
 sql > SELECT OWNER,TABLE_NAME,STATTYPE_LOCKED
         FROM DBA_TAB_STATISTICS
         WHERE STATTYPE_LOCKED IS NOT NULL;

TO Unlock all the tables in a schema at once :
sql> exec dbms_stats.unlock_schema_stats(‘schema_owner’);
e.g : sql> exec dbms_stats.unlock_schema_stats(‘apps’);

TO Unlock all Individual  tables in a schema at once  

sql> exec dbms_stats.unlock_schema_stats(‘table_owner’,'table_name’);
e.g : sql > exec dbms_stats.unlock_schema_stats(‘AR’,'AR_REV_REC_QT’);

There are two reasons for that error message:

1 ) There are duplicate rows on FND_HISTOGRAM_COLS table for JE_BE_LINE_TYPE_MAP table.
Because of this problem, FND_STATS tries to gather histogram information using wrong command and it fails with ora-20001 errors.
Following SQL should have returned one row, not two.
SQL> select a.column_name, nvl(a.hsize,254) hsize
from FND_HISTOGRAM_COLS a
where table_name = ‘JE_BE_LINE_TYPE_MAP’
order by column_name;
COLUMN_NAME HSIZE
—————————— ———-
SOURCE 254
SOURCE 254
 2) Column does not exist on the table but still listed in FND_HISTOGRAMS_COL table.
Solution:
Find out all duplicates and/or obsolete rows in FND_HISTOGRAM_COLS and delete one of them.
Remember to take backup of the FND_HISTOGRAM_COLS table before deleting any data.
– identify duplicate rows
select table_name, column_name, count(*)
from FND_HISTOGRAM_COLS
group by table_name, column_name
having count(*) > 1;

– Use above results on the following SQL to delete duplicates
delete from FND_HISTOGRAM_COLS
where table_name = ‘&TABLE_NAME’
and  column_name = ‘&COLUMN_NAME’
and rownum=1;

– Use following SQL to delete obsoleted rows
delete from FND_HISTOGRAM_COLS
where (table_name, column_name) in
  (
   select hc.table_name, hc.column_name
   from FND_HISTOGRAM_COLS hc , dba_tab_columns tc
   where hc.table_name  =’&TABLE_NAME’
   and hc.table_name= tc.table_name (+)
   and hc.column_name = tc.column_name (+)
   and tc.column_name is null
  );