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BugZero found this defect 227 days ago.
When updating Veeam Backup & Replication the Configuration Check fails with either: Failed to connect to PostgreSQL server localhost:5432. An existing connection was forcibly closed by the remote host SSPI authentication failed for user
The account being used to run the update installer is not authorized to access the Veeam Backup & Replication configuration database.
Review KB4542: "SSPI authentication failed for user"