How to fix Error 3443 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 3443 — Database Marked for Standby or Read-Only Use

Why This Error Happens

This error occurs when SQL Server attempts to write to or modify a database that is currently in STANDBY or READ_ONLY mode, typically as part of a log shipping configuration. The restore process places the secondary database in a state where it accepts transaction log restores but rejects direct write operations from users or applications. This conflict commonly arises when an application connection string incorrectly points to the secondary (standby) server instead of the primary, or when a scheduled job attempts to write to the database during an active restore sequence.

Step-by-Step Resolution Guide

Step 1: Verify the Database State and Role

  • Open SQL Server Management Studio (SSMS) and connect to the instance reporting the error.
  • Run SELECT name, state_desc, is_read_only FROM sys.databases WHERE name = 'YourDatabaseName'; to confirm if the database is in STANDBY or READ_ONLY state.
  • Check if this database is part of a Log Shipping or Always On Availability Group topology via SSMS > Management > Log Shipping Monitor.

Step 2: Redirect Write Operations to the Primary Server

  • Identify the primary (production) server in the log shipping or replication topology.
  • Update the application’s connection string or DNS alias (CNAME) to point to the primary instance rather than the standby instance.
  • On Windows Server 2025, check C:\Windows\System32\drivers\etc\hosts or your DNS management console if a hardcoded alias is causing the misdirection.

Step 3: Adjust Standby Database Permissions (If Read-Only Access Is Intended)

  • If the database is intentionally read-only for reporting purposes, ensure the application or user is only executing SELECT statements and not INSERT, UPDATE, or DELETE commands.
  • Modify the application logic to separate read-only reporting queries from transactional write operations.
  • If write access is required, work with your DBA to remove the database from the log shipping secondary role using RESTORE DATABASE [YourDatabaseName] WITH RECOVERY; (Note: this will break the log shipping chain).

Step 4: Review SQL Server Agent Jobs

  • Open SQL Server Agent > Jobs in SSMS and look for any ETL, maintenance, or custom jobs scheduled to run write operations against the standby database.
  • Disable or reschedule any job incorrectly targeting the secondary server.
  • Check the SQL Server Error Log located at C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG for the specific job or login ID that triggered the write attempt.

Alternative or Verification Steps

  • To verify the fix, run a test transaction (e.g., a harmless UPDATE to a test table) against the primary server connection string and confirm it completes without triggering Error 3443.
  • If the error persists despite connecting to the correct primary server, check for an orphaned Availability Group listener or stale DNS cache entry by running ipconfig /flushdns on the Windows Server 2025 host and retesting the connection.