How to fix Error 2309 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 2309 – “The value of ‘%ls’ is not a valid number”

Why This Error Happens

This error typically occurs when SQL Server Setup or a configuration script encounters a parameter value that is expected to be numeric (such as a port number, instance ID, or memory allocation value) but instead receives a blank, corrupted, or non-numeric string. This is commonly caused by malformed command-line arguments passed during an unattended installation, corrupted entries in the ConfigurationFile.ini, or locale/regional settings on Windows Server 2025 / Windows 11 that use a different decimal or thousands separator than SQL Server expects. In rare cases, it can also stem from a corrupted registry key under the SQL Server instance hive that stores a numeric configuration value.

Step-by-Step Resolution Guide

Step 1: Validate the Configuration File or Command-Line Parameters

  • Open the ConfigurationFile.ini typically located at C:\Program Files\Microsoft SQL Server\160\Setup Bootstrap\Log\<timestamp>\ConfigurationFile.ini.
  • Check numeric fields such as SQLSVCINSTANTFILEINIT, TCPPORT, NPENABLED, ASCOLLATION, and SQLBACKUPDIR sizing values for stray spaces, quotation marks, or non-numeric characters.
  • If running from PowerShell or CMD, re-verify any /PORT=, /INSTANCEID=, or /SQLBACKUPDIR= switches do not contain accidental text or environment variable expansion errors.
  • Example: setup.exe /ACTION=Install /TCPPORT=1433 instead of /TCPPORT="1433 ".

Step 2: Check Regional and Language Settings

  • Go to Control Panel > Region > Formats and confirm the decimal symbol is set to a period (.) if SQL Server Setup expects US-style numeric formatting.
  • Navigate to Administrative > Change system locale and ensure it matches the supported locale for your SQL Server 2025 build.
  • Restart the server after changing locale settings to ensure the change propagates to the SQL Server Setup process.

Step 3: Inspect and Repair Registry Numeric Keys

  • Open regedit and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\<InstanceID>\MSSQLServer\Parameters.
  • Look for any parameter value (such as SQLArg0, SQLArg1) that should be numeric but shows blank, text, or unexpected characters.
  • Correct the value manually or restore it from a known-good backup of the registry hive, then restart the SQL Server (MSSQLSERVER) service.

Step 4: Re-run Setup with Logging Enabled

  • Launch Setup with verbose logging: setup.exe /ACTION=Install /INDICATEPROGRESS /QUIET /FEATURES=SQL /SkipRules=RebootRequiredCheck /ENU.
  • Review the detailed log at Summary.txt and Detail.txt in the Setup Bootstrap Log folder to pinpoint exactly which numeric parameter triggered Error 2309.
  • Correct the identified parameter and re-run the installation.

Alternative or Verification Steps

  • After applying fixes, re-run setup.exe /ACTION=Install and confirm no Error 2309 appears in the Setup Summary log; successful completion should show “Setup completed successfully” status.
  • As an alternative, use SQL Server Configuration Manager to manually set affected numeric properties (e.g., TCP port under SQL Server Network Configuration > Protocols) instead of relying on the installer-provided values.