YaST and Zypper Migration Fails on SLES 15 SP4 to SP5 on SUMA-Registered Clients

SUSE Linux Enterprise Server 15 all Service Packs
SUSE Linux Enterprise Server 12 all Service Packs

SUSE Multi Linux Manager 4.3

The SLES 15 SP4 system is registered to the SUMA 4.3 server as a client.

When the customer migrate SLES 15 SP4 to SP5 using the YaST and zypper migration commands, it is showing error messages 

1. yast migration 

        │ The system is not registered,        │
        │ to run the online migration you need │
        │ to register the system first.        │

2. zypper migration

# zypper migration

Executing '/usr/bin/zypper patch-check --updatestack-only'

Loading repository data...
Reading installed packages...

0 patches needed (0 security patches)

Executing '/usr/bin/zypper ref'
...
Executing '/usr/bin/zypper --disable-repositories --xmlout --non-interactive products -i'

Executing '/usr/bin/zypper --no-refresh --non-interactive install --no-recommends --auto-agree-with-product-licenses -t product SLES'

Can't get available migrations from server: Credentials file is missing
'/usr/lib/zypper/commands/zypper-migration' exited with status 1

3. SUSCConnect --status

# SUSEConnect --status
[{"identifier":"sle-module-basesystem","version":"15.4","arch":"x86_64","status":"Not Registered"},{"identifier":"sle-module-server-applications","version":"15.4","arch":"x86_64","status":"Not Registered"},{"identifier":"sle-module-desktop-applications","version":"15.4","arch":"x86_64","status":"Not Registered"},{"identifier":"sle-manager-tools","version":"15","arch":"x86_64","status":"Not Registered"},{"identifier":"SLES","version":"15.4","arch":"x86_64","status":"Not Registered"}]

Because customer client SLES 15 SP4  is registered to the SUSE Multi Linux Manager(SMLM - previous SUSE Manager ), migrate the client using SMLM Web UI

Product Migration

 https://documentation.suse.com/suma/4.3/en/suse-manager/client-configuration/client-upgrades-product-migration.html

After the customer bootstraps the SLES client registered to the SCC, the SCC registration information is removed, so the YaST and zypper OS Migration commands no longer work from the client side.