How to fix Error 4153 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 4153

Why This Error Happens

Error 4153 occurs when SQL Server encounters a data type mismatch that it cannot implicitly convert, typically during BULK INSERT, OPENROWSET, or SELECT INTO operations where the source data format doesn’t align with the destination column’s defined data type. This is commonly caused by incorrect format file definitions, mismatched column ordinals between source and destination, or attempting to map incompatible types (such as treating a varchar field as datetime or XML as nvarchar without proper casting). Corrupted or outdated format files (.fmt or .xml) used in bulk import operations are also a frequent root cause.

Step-by-Step Resolution Guide

Step 1: Verify the Source and Destination Schema

  • Run sp_help 'YourTableName' in SQL Server Management Studio (SSMS) to inspect the exact data types and ordinal positions of the destination table.
  • Compare this against the source file or query output column-by-column to identify the specific type mismatch referenced in the error.
  • Pay close attention to precision/scale differences (e.g., decimal(10,2) vs float).

Step 2: Inspect and Regenerate the Format File

  • If using BULK INSERT or bcp, locate the format file (commonly stored in paths like C:\SQLData\Import\format.xml).
  • Regenerate the format file using the bcp utility to ensure it matches the current table schema:
  • bcp YourDatabase.dbo.YourTable format nul -c -x -f C:\SQLData\Import\newformat.xml -t, -S YourServerName -T
  • Open the new XML file and verify the <COLUMN> tags match the SOURCE and xsi:type attributes correctly.

Step 3: Apply Explicit Type Casting in the Query

  • If the error occurs in a SELECT INTO or INSERT...SELECT statement, modify the query to explicitly cast the problematic column.
  • Example syntax: SELECT CAST(SourceColumn AS NVARCHAR(50)) FROM SourceTable.
  • Save the script in SSMS and re-run the query to confirm the cast resolves the conflict.

Step 4: Check for XML/JSON Type Conflicts

  • If the error involves XML or JSON data types, ensure the destination column is not attempting to treat raw text as structured XML without validation.
  • Use CONVERT(XML, YourColumn) explicitly rather than relying on implicit conversion during the insert.
  • Restart the SQL Server Database Engine service via services.msc on Windows Server 2025 if schema caching causes the old type definition to persist after changes.

Alternative or Verification Steps

  • Verification: Re-run the original BULK INSERT or SELECT INTO statement; if successful, query the top 10 rows of the destination table using SELECT TOP 10 * FROM YourTable to ensure data integrity and correct type casting.
  • Alternative: If the format file continues to cause issues, bypass it entirely by using the OPENROWSET(BULK...) function with explicit WITH schema declarations to force the correct data types during import.