How to fix Error 2315 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 2315 — “The attribute “”%ls”” should have a string value.”

Why This Error Happens

Error 2315 occurs when the SQL Server Windows Installer (MSI) or an internal configuration reader encounters an attribute in the installer database, configuration file, or XML-based setup manifest that is malformed, non-string, or null where a string value is strictly expected. This typically stems from a corrupted installer cache file, a damaged .msi/.msp patch, or improperly edited configuration XML (such as ConfigurationFile.ini or setup manifest attributes) during an upgrade or repair operation on SQL Server 2025. It can also surface when third-party deployment tools inject invalid registry or property values into the Windows Installer transaction.

Step-by-Step Resolution Guide

Step 1: Verify and Repair the Windows Installer Cache

  • Navigate to C:\Windows\Installer and confirm the cached .msi files referenced by SQL Server setup are not zero-byte or missing.
  • Run msiexec /unreg followed by msiexec /regserver in an elevated Command Prompt to re-register the Windows Installer service.
  • Use the SQL Server Installation Center to run a Repair operation: Setup.exe /ACTION=Repair /INSTANCENAME=MSSQLSERVER.

Step 2: Validate the Setup Configuration File

  • Open the ConfigurationFile.ini (typically found in %ProgramFiles%\Microsoft SQL Server\160\Setup Bootstrap\Log\<timestamp>\) and check for blank, null, or numeric values assigned to attributes expecting strings (e.g., INSTANCENAME, FEATURES, SQLSYSADMINACCOUNTS).
  • Remove any malformed or duplicate key-value pairs and ensure all string attributes are wrapped in quotes where required.
  • Save the file in ANSI/UTF-8 encoding (not UTF-16) to avoid parser misreads.

Step 3: Clear Corrupted Setup Bootstrap Cache

  • Delete temporary bootstrap cache at %ProgramFiles%\Microsoft SQL Server\160\Setup Bootstrap\Cache\ (back up first if needed).
  • Clear the %TEMP% directory for the account running setup to eliminate stale installer fragments.
  • Re-launch Setup.exe as Administrator to force regeneration of a clean cache.

Step 4: Check Windows Registry for Invalid Installer Properties

  • Open regedit and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\.
  • Locate the GUID associated with your SQL Server 2025 instance and inspect the InstallProperties key for any non-string (REGDWORD/REGBINARY) values mistakenly placed where REG_SZ is expected.
  • Correct the data type via right-click → Modify, ensuring the value type matches REG_SZ.

Alternative or Verification Steps

  • After applying fixes, re-run setup with verbose logging: Setup.exe /ACTION=Install /INDICATEPROGRESS /Log "C:\SQLLogs\setup_verbose.log" and confirm Error 2315 no longer appears in the generated log.
  • If the issue persists, download a fresh copy of the SQL Server 2025 installation media (the current ISO may be corrupted) and re-attempt setup from a new mounted drive letter.