How to fix Error 4855 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: SQL Server Error 4855

Why This Error Happens

Error 4855 occurs when the SQL Server bulk copy program (BCP) or BULK INSERT operation encounters an XML format file that doesn’t conform to the expected schema structure. This typically happens due to manual editing errors in the format file, corruption during file transfer (such as FTP in ASCII mode instead of binary), or version mismatches between the format file schema and the SQL Server 2025 engine. Unexpected elements often result from mixing non-XML format file syntax with XML format files, or from stray characters/tags introduced by text editors that auto-format XML content.

Step-by-Step Resolution Guide

Step 1: Validate the Format File Structure

  • Open the format file referenced in the error message using a plain text editor (Notepad++ or VS Code), not Word or an editor that may inject hidden formatting.
  • Confirm the root element is correctly declared, e.g., <BCPFORMAT xmlns="http://schemas.microsoft.com/sqlserver/2004/bulkload/format" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">.
  • Check the exact line number referenced in the error (Line %d) and inspect it for malformed or unexpected tags like stray <RECORD> or <ROW> elements outside their proper nesting.

Step 2: Regenerate the Format File Using BCP

  • Instead of manually editing, regenerate a clean format file directly from SQL Server 2025 using the following command in PowerShell or Command Prompt:
  • bcp YourDatabase.dbo.YourTable format nul -c -x -f C:\BCP\NewFormatFile.xml -t, -S YourServerName -T
  • This creates a schema-valid XML format file that matches the current table structure, eliminating hand-typed syntax errors.
  • Replace the corrupted or hand-edited file at its original path (e.g., C:\BCP\Format\OriginalFile.xml) with this newly generated version.

Step 3: Check for Encoding and Hidden Character Issues

  • Re-save the file explicitly as UTF-8 without BOM (Byte Order Mark), since Windows Server 2025 and Windows 11 text editors sometimes insert a BOM that SQL Server’s XML parser misinterprets as an unexpected element at Line 1.
  • Use the command Get-Content C:\BCP\Format\OriginalFile.xml -Encoding Byte -TotalCount 3 in PowerShell to inspect the first bytes of the file and confirm no BOM markers (EF BB BF) are present.
  • If BOM is detected, re-export the file using [System.IO.File]::WriteAllLines("C:\BCP\Format\Fixed.xml", (Get-Content "C:\BCP\Format\OriginalFile.xml"), (New-Object System.Text.UTF8Encoding $false)).

Step 4: Verify Schema Namespace Compatibility

  • Ensure the format file’s namespace declaration matches the version supported by SQL Server 2025; using an outdated 2003 or 2005 schema reference can trigger unexpected element errors on newer builds.
  • Update the xmlns attribute in the <BCPFORMAT> tag to the current namespace supported by your SQL Server build, found in Microsoft’s official BCP documentation for your exact version.

Alternative or Verification Steps

  • Run the BULK INSERT or BCP command again after replacing the file and confirm no Error 4855 appears in the SQL Server Error Log (Get-Content "C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG" for most recent builds).
  • As an alternative, switch to a non-XML (native) format file by omitting the -x flag in the bcp command, which bypasses XML parsing entirely and avoids schema-related element errors.