After GI upgrade flashgrid-cluster shows wrong diskgroup status

Problem:

I have upgraded Oracle GI from 12c to 19c. ASM is up and diskgroups are mounted, but flashgrid-cluster still shows that diskgroups are not mounted on any node:

[root@rac1 ~]# flashgrid-cluster
FlashGrid 21.8.67.66809 #707efdc10a212421dbd3737ef8e693ae14c15964
License: Active, Marketplace
Licensee: Flashgrid Inc.
Support plan: 24x7
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FlashGrid running: OK
Clocks check: OK
Configuration check: OK
Network check: OK

Querying nodes: rac1, rac2, racq ...

Cluster Name: mariGIMR
Cluster status: Warning
-------------------------------------------------------------
Node  Status   ASM_Node  Storage_Node  Quorum_Node  Failgroup
-------------------------------------------------------------
rac1  Warning  Yes       Yes           No           RAC1
rac2  Warning  Yes       Yes           No           RAC2
racq  Warning  No        No            Yes          RACQ
-------------------------------------------------------------
-----------------------------------------------------------------------------
GroupName  Status  Mounted  Type  TotalMiB  FreeMiB  OfflineDisks  LostDisks  Resync  ReadLocal  Vote
-----------------------------------------------------------------------------
GRID     Warning  No  N/A   N/A   N/A    N/A    N/A  N/A     N/A        N/A
-----------------------------------------------------------------------------

Solution:

After upgrade, you should restart flashgrid_asm service on all nodes, it does not require downtime:

[root@rac1 ~]# systemctl restart flashgrid_asm
[root@rac2 ~]# systemctl restart flashgrid_asm

Check the status again:

...
-----------------------------------------------------------------------------
GroupName  Status  Mounted   Type    TotalMiB  FreeMiB  OfflineDisks  LostDisks  Resync  ReadLocal  Vote
-----------------------------------------------------------------------------
GRID    Good    AllNodes  NORMAL  204800    154336   0   0  No Enabled    3/3
-----------------------------------------------------------------------------