How to fix Error 3250 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 3250 – “The value ‘%d’ is not within range for the %ls parameter”

Why This Error Happens

This error typically occurs during backup or restore operations when a specified parameter value—such as BLOCKSIZE, BUFFERCOUNT, MAXTRANSFERSIZE, or a file/device number—falls outside the acceptable range defined by the SQL Server Database Engine. It commonly arises from manually scripted T-SQL backup/restore commands where a value was mistyped, copied from an incompatible script, or inherited from a legacy SQL Server version with different parameter boundaries. In some cases, corrupted backup media headers or mismatched media family counts can also trigger this validation failure.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Parameter and Value

  • Review the full error message text to extract the exact parameter name (%ls) and value (%d) that triggered the failure.
  • Check the SQL Server Error Log via C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG for the full context of the failed statement.
  • Locate the T-SQL script (BACKUP, RESTORE, or WITH options) that was executed immediately before the error appeared.

Step 2: Validate Parameter Ranges Against SQL Server 2025 Documentation

  • Confirm BUFFERCOUNT is a positive integer and not set unreasonably high relative to available memory (excessive values can exceed internal limits).
  • Verify MAXTRANSFERSIZE is set in valid increments (65536 up to 4194304 bytes) and is a multiple of 65536.
  • Check BLOCKSIZE values against supported device block sizes (typically 512 to 65536 bytes).
  • If using FILE = or MEDIANAME = options, ensure referenced file/media numbers correspond to an existing, correctly ordered backup set.

Step 3: Correct and Re-run the T-SQL Statement

  • Edit the script in SQL Server Management Studio (SSMS) to correct the invalid parameter value.
  • Example correction:
  BACKUP DATABASE [YourDB]
  TO DISK = 'D:\Backups\YourDB.bak'
  WITH BUFFERCOUNT = 50, MAXTRANSFERSIZE = 1048576;
  • Execute the corrected script and monitor for successful completion in the Messages tab.

Step 4: Check for Corrupted or Incompatible Backup Media

  • Run RESTORE VERIFYONLY FROM DISK = 'D:\Backups\YourDB.bak'; to confirm the backup file integrity before attempting a full restore.
  • If verification fails, regenerate the backup file from a known-good source or a different backup set.

Step 5: Review Maintenance Plans and Automation Scripts

  • Open SQL Server Agent Jobs in SSMS and inspect any scheduled backup/restore jobs for hardcoded parameter values.
  • Update any PowerShell or dbatools scripts (e.g., Backup-DbaDatabase) that may be passing out-of-range values programmatically.

Alternative or Verification Steps

  • Re-run the corrected backup/restore command and confirm it completes with “processed successfully” messages and no Error 3250 in the ERRORLOG.
  • If the issue persists, strip the command down to default parameters (no BUFFERCOUNT, BLOCKSIZE, or MAXTRANSFERSIZE) to isolate whether a specific option is still causing the range violation.