ORA-01664: unable to extend index

ORA-01664: unable to extend index JTF.JTF_IH_ACTIVITIES_N6 by 16 in tablespace APPS_TS_TX_IDX.
Solution:-
It means that index has need to grow in space and tablespace APPS_TS_TX_IDX is full .
You need to add datafille , This is regular daily dba work nothing to worry about.
Action plan :
1.First verify where are APPS_TS_TX_IDX datafiles --> select file_name from dba_data_files where tablesapce_name='APPS_TS_TX_IDX';
2.Verify you have enough space in the filsystem .
3. Add datafile --> alter tablespace APPS_TS_TX_IDX add datafile '/path to datafile' size XXXM;