Load balancing failed to find a valid mailbox database. error

I'm adding a new mailbox. I click Existing user.
Selecting a user

I click save

i use DAG
I can choose base itself. but then an error occurs

owa too not open

X-ClientId: 9DBD1C75698E40849C5C55AD660A1B4A
request-id 1cccbb15-a3a6-4e53-9dfa-8442f38893e2
X-OWA-Error Microsoft.Exchange.Data.Storage.UserHasNoMailboxException
X-OWA-Version 15.2.1258.28
X-FEServer NODE4
X-BEServer NODE4
Date:20.02.2024 8:49:25