Summary: After upgrading Veeam Backup & Replication, the PostgreSQL service may fail authentication for the postgres user when using SSPI (Windows integrated authentication).

Symptoms: During upgrade or Veeam service startup, the following error appears in logs:

FATAL: SSPI authentication failed for user "postgres"

Root Cause: The local Windows account running the upgrade (often a local Administrator) isn’t mapped to the postgres database role. Veeam’s installer attempts SSPI authentication via the Windows user, which PostgreSQL rejects unless explicitly mapped.

Solution: Add a mapping for the local admin account to the postgres role in the PostgreSQL ident map configuration file.

Steps:

• 1 - Open the file:

C:\Program Files\PostgreSQL\15\data\pg_ident.conf

• 2 - Append a line mapping your Windows user to the postgres role:

# Map local Windows admin to postgres role
map_admin   YOUR-PC\Administrator   postgres

• 3 - Verify that pg_hba.conf uses the matching map:

host    all    postgres    127.0.0.1/32    sspi    map=map_admin

• 4 - Restart the PostgreSQL service:

net stop postgresql-x64-15
net start postgresql-x64-15

Verification: Run the following test to confirm:

psql -U postgres -h localhost

You should connect without SSPI authentication errors.

Notes:

• This typically happens on standalone or lab environments using local Windows accounts.
• In domain environments, ensure the domain account is mapped instead.
• File paths may differ depending on PostgreSQL version or Veeam installation directory.

References:

• PostgreSQL Docs: SSPI Authentication
• Veeam KB: PostgreSQL Authentication Issues