Hive drop partition issue error in metastore query

[#1]

I'm getting a curious error when i'm trying to drop partitions from a managed table:

hive> ALTER TABLE table_name DROP PARTITION (date_val < '2017-01-28');

FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. Exception thrown when executing query : SELECT "A0"."PART_NAME","A0"."PART_NAME" AS "NUCORDER0" FROM "PARTITIONS" "A0" LEFT OUTER JOIN "TBLS" "B0" ON "A0"."TBL_ID" = "B0"."TBL_ID" LEFT OUTER JOIN "DBS" "C0" ON "B0"."DB_ID" = "C0"."DB_ID" WHERE "C0"."NAME" = ? AND "B0"."TBL_NAME" = ? ORDER BY "NUCORDER0"

As some basic troubleshooting I've tried:

msck repair table <table_name> (STILL RUNNING)

I can run a manual query against the metastore that WORKS if I replace the "?" in the above error with real values

Super duper confused, any help/suggestions would be great

[#2]

Fixed this by discovering my date_val column had the '__HIVE_DEFAULT_PARTITION__' and then was failing on this alter because the value didn't work with the column datatype (DATE vs STRING)

I got around this by changing the column to string, drop the partition for the default and then change it back to date. Got some pointers from here:

http://www.ericlin.me/how-to-drop-hives-default-partition-__hive_default_partition__-with-int-partit...