Sigh...
The command "cat /proc/mdstat" confirms that md127 is no more present:
Code
root@DIYNAS-OMV:~# cat /proc/mdstat
Personalities : [raid0] [raid6] [raid5] [raid4] [linear] [multipath] [raid1] [raid10]
md0 : active raid5 sdb[2] sda[3] sdf[0] sde[1] sdc[4]
23441567744 blocks super 1.2 level 5, 512k chunk, algorithm 2 [5/5] [UUUUU]
bitmap: 0/44 pages [0KB], 65536KB chunk
...but the "grow" fails again (but with different message)