Split Partition which have data on it

Hi All,

I have a question, I have a table where the last parition was created by March 2021 let's called it DATE_20210301 and every data from March 2021 was entering into the max partition column let's called it MAX_999999, Now i need to split the paritions MAX_999999, with this command

ALTER TABLE TB_TRANSACTION

SPLIT PARTITION MAX_999999 AT

(20210401)

INTO (PARTITION DATE_20210401 ,PARTITION MAX_999999 ) parallel 4;

After it's completed when i checked the alert log show this warning :

Some indexes or index [sub]partitions of table TB_TRANSACTION have been marked unusable, and when i check my index it's become unusable, and i have to rebuild those index.