cannot mdadm --run RAID5 array

I am receiving an error using mdadm --assemble ,--run and --detail

mdadm: Unknown keyword INACTIVE-ARRAY

twice in the row AFTER successfully checking the array using
mdadm --detail

It looks as two errors in one - unknown keyword and INACTIVE-ARRAY

A syntax error I fail to notice ??

Would appreciate some assistance in resolving THIS and this issue only.

Here is my command and output

Code:f@f-SATA:~$ sudo mdadm --assemble /dev/md100
[sudo] password for f:
mdadm: Unknown keyword INACTIVE-ARRAY
mdadm: Unknown keyword INACTIVE-ARRAY
f@f-SATA:~$ sudo mdadm --detail /dev/md100
mdadm: Unknown keyword INACTIVE-ARRAY
mdadm: Unknown keyword INACTIVE-ARRAY
/dev/md100:
Version : 1.2
Creation Time : Wed Nov 4 14:30:48 2020
Raid Level : raid5
Array Size : 1021952 (998.17 MiB 1046.48 MB)
Used Dev Size : 510976 (499.08 MiB 523.24 MB)
Raid Devices : 3
Total Devices : 3
Persistence : Superblock is persistent

Update Time : Thu Nov 5 17:33:59 2020
State : clean
Active Devices : 3
Working Devices : 3
Failed Devices : 0
Spare Devices : 0

Layout : left-symmetric
Chunk Size : 512K

Name : f-SATA:100 (local to host f-SATA)
UUID : 3f382a10:e888bf49:471caae8:029ecba3
Events : 20

Number Major Minor RaidDevice State
0 8 161 0 active sync /dev/sdk1
1 8 162 1 active sync /dev/sdk2
3 8 163 2 active sync /dev/sdk3
f@f-SATA:~$Thanks