License check failure

[quyennv0405]

Reason: transient license check failure: downgrade to legacy code-base is not supported, reinstall server or use non-legacy license
my customer buy new license, when old license expired.
new license after update not update and above error appear.
Can someone support me

 

[Richard G]

my customer buy new license, when old license expired.

Where did he buy the license?

 

[quyennv0405]

Where did he buy the license?

I know the cause when using license key of old system. thanks!