How to fix Error 4898 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 4898 – Bulk Load CSV Format File Issue

Why This Error Happens

Error 4898 occurs when the non-XML format file used for a BULK INSERT or bcp operation defines a field type (such as SQLINT, SQLDECIMAL, or other non-character types) for a column when the CSV format option has been explicitly specified. SQL Server 2025 enforces strict validation when FORMAT = 'CSV' is used, requiring every field in the format file to be typed as SQLCHAR or SQLNCHAR with a defined terminator. This typically happens when an older non-XML format file (generated for native or character format) is reused with the newer CSV-specific bulk load syntax without being regenerated or manually edited.

Step-by-Step Resolution Guide

Step 1: Inspect the Existing Format File

  • Open the .fmt file referenced in your BULK INSERT or bcp command in a text editor (e.g., Notepad++ or VS Code).
  • Locate the column definitions and check the host file data type column for any value other than SQLCHAR or SQLNCHAR.
  • Note the specific source column number mentioned in the error message (%d) and cross-reference it in the file.

Step 2: Regenerate the Format File Using the Correct Flags

  • Use the bcp utility to regenerate a CSV-compliant format file rather than editing manually.
  • Run the following command from an elevated PowerShell or Command Prompt on Windows Server 2025/Windows 11:
  bcp YourDatabase.dbo.YourTable format nul -c -t, -r \n -f C:\ImportFiles\NewFormat.fmt -S YourServerName -T
  • Confirm the generated file now lists SQLCHAR for every field type entry, which satisfies the CSV format requirement.

Step 3: Manually Correct Field Types (If Regeneration Isn’t an Option)

  • If you must keep a custom format file, manually change every instance of SQLINT, SQLDECIMAL, SQLDATETIME, etc., to SQLCHAR.
  • Ensure each row has a proper terminator defined (e.g., , for mid-row fields and \r\n for the final field).
  • Save the file with UTF-8 or ANSI encoding matching your source CSV file’s encoding to avoid secondary parsing errors.

Step 4: Re-run the Bulk Load Operation

  • Execute the BULK INSERT or bcp command again, explicitly pointing to the corrected format file.
  • Example T-SQL syntax:
  BULK INSERT dbo.YourTable
  FROM 'C:\ImportFiles\data.csv'
  WITH (
      FORMATFILE = 'C:\ImportFiles\NewFormat.fmt',
      FORMAT = 'CSV',
      FIRSTROW = 2
  );
  • Confirm the operation completes without triggering Error 4898.

Alternative or Verification Steps

  • Verify the fix by checking SQL Server’s Activity Monitor or querying sys.dm_exec_requests during the load to confirm the process completes and rows land correctly in the target table.
  • As an alternative, skip the format file entirely for simple CSV imports and use BULK INSERT with only FORMAT = 'CSV', FIELDTERMINATOR, and ROWTERMINATOR options, letting SQL Server infer character-based parsing automatically.