Solved: How do I fix ORA-01502: Index or partition of such index is in unusable state error

Problem Symptom

I get the below error when inserting data in the table with 1 primary key and 3 foreign keys, 1st row below is the Primary key index and I do not know the Partition. Why is this happening & How to fix this issue?

1st row below is the Primary key index and I do not know the Partition

The detailed error message is as below:

ORA-01502: Index or partition of such index is in unusable state error

ORA-01502: Index or partition of such index is in unusable state error

Follow the below solution steps to resolve ORA-01502: Index or partition of such index is in unusable state error.

Solution

Since this index was not partitioned no name was passed and it worked. The following command fixed the error:
ALTER INDEX REBUILD;