How to fix Error 4856 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 4856 – “Unexpected Info Item” in Format File

Why This Error Happens

Error 4856 occurs when the SQL Server bulk copy program (bcp) or BULK INSERT operation parses a non-XML format file and encounters a field entry that does not conform to the expected structure for that line. This typically results from a manually edited format file where a column definition is missing a required token (such as the host file data type, prefix length, data length, terminator, server column order, or column name), or where extra/misplaced whitespace and delimiters have corrupted the token count. It can also occur if a format file generated by one SQL Server version (or a different collation/locale setting) is used against a table schema that has since changed column count or structure.

Step-by-Step Resolution Guide

Step 1: Regenerate the Format File from Scratch

  • Do not hand-edit an existing format file; instead regenerate it using bcp to guarantee the token structure matches your current table schema.
  • Run the following from Command Prompt on Windows Server 2025 / Windows 11:
bcp YourDatabase.dbo.YourTable format nul -c -f C:\SQLData\YourTable.fmt -S YourServerName -T
  • This creates a clean, correctly tokenized non-XML format file at C:\SQLData\YourTable.fmt.

Step 2: Validate the Field Count on the Flagged Line

  • Open the format file in a text editor (Notepad++ or VS Code) and navigate to the exact line number reported in the error message.
  • Confirm each row (after the header lines) contains exactly 9 whitespace-separated fields in this order: HostFileFieldOrder, HostFileDataType, PrefixLength, HostFileDataLength, Terminator, ServerColumnOrder, ServerColumnName, Collation.
  • Remove any stray tabs, extra spaces, or trailing characters that may have inserted a 9th or 10th phantom token.

Step 3: Confirm the Format File Version Header Matches Your SQL Server Instance

  • Check the very first line of the format file — it should read 14.0 (or the version matching SQL Server 2025) and the second line should match the exact column count of the target table.
  • If the column count on line 2 doesn’t match the number of row entries below it, SQL Server will misread subsequent lines as malformed, triggering Error 4856.
  • Update the column count manually or regenerate via Step 1 if the table schema was altered (columns added/dropped) after the original format file was created.

Step 4: Re-run the Bulk Operation with Verbose Error Checking

  • Execute the BULK INSERT or bcp command again, pointing explicitly to the corrected .fmt file:
BULK INSERT YourDatabase.dbo.YourTable
FROM 'C:\SQLData\YourTable.csv'
WITH (FORMATFILE = 'C:\SQLData\YourTable.fmt', FIRSTROW = 2);
  • Capture full output to confirm no further line-parsing errors are thrown.

Alternative or Verification Steps

  • Verify success by checking SELECT COUNT(*) FROM YourDatabase.dbo.YourTable before and after the load to confirm the expected row count was inserted without truncation errors.
  • If the non-XML format file continues to cause issues, switch to an XML-based format file (bcp ... format nul -x -c -f YourTable.xml -S YourServerName -T), which is less prone to manual token corruption and easier to validate structurally.