How to fix Error 5355 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 5355

Why This Error Happens

Error 5355 occurs when SQL Server’s BULK INSERT or OPENROWSET(BULK…) operation receives an empty string (”) for a format-related option—such as FIELDTERMINATOR, ROWTERMINATOR, or FORMATFILE—when the specified data format (CSV, native, or JSON) and PARSERVERSION require a non-empty value. This is typically caused by dynamically generated SQL scripts, ETL tools, or ORM frameworks that pass blank variables instead of NULL or a valid delimiter. It can also surface after migrating scripts to PARSERVERSION=’2.0′, which enforces stricter validation on format options than the legacy parser.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Statement and Option

  • Check the SQL Server error log or SSMS output for the exact option name referenced in the error message (e.g., FIELDTERMINATOR, ROWTERMINATOR, FORMATFILEDATASOURCE).
  • Run the failing query manually in SSMS to isolate which parameter is being passed as an empty string.
  • Review any stored procedures or application code that constructs the BULK INSERT/OPENROWSET statement dynamically, especially string concatenation logic.

Step 2: Correct the Parameter Values

  • Replace empty string assignments with valid values or NULL. For example:
  BULK INSERT dbo.MyTable
  FROM 'C:\Data\import.csv'
  WITH (
      FORMAT = 'CSV',
      FIELDTERMINATOR = ',',   -- must not be ''
      ROWTERMINATOR = '\n',
      PARSER_VERSION = '2.0'
  );
  • If the application passes variables, ensure default values in config files (e.g., appsettings.json or .env) are not blank strings for delimiter/terminator fields.
  • For FORMATFILE-based imports, verify the path (e.g., C:\SQLData\FormatFiles\import.fmt) is correctly populated and not an empty path variable.

Step 3: Validate PARSER_VERSION Compatibility

  • If using PARSER_VERSION = ‘2.0’, confirm all required options for CSV format are explicitly set, since the 2.0 parser does not fall back to defaults like the legacy ‘1.0’ parser.
  • Temporarily test with PARSER_VERSION = ‘1.0’ to confirm whether the issue is version-specific.
  • Update documentation or templates used by developers to include mandatory non-empty values for all format-related clauses.

Step 4: Rebuild and Test the Import Script

  • Clear any cached execution plans related to the procedure using DBCC FREEPROCCACHE (only in non-production environments) to ensure the corrected script is used.
  • Re-run the BULK INSERT/OPENROWSET command from SSMS or via the Windows Server 2025 task scheduler job to confirm success.

Alternative or Verification Steps

  • Verify the fix by re-executing the import with SET STATISTICS IO ON; and confirming zero errors in sys.dm_exec_requests or the SQL error log.
  • If the error persists, bypass dynamic parameter injection entirely and hardcode a known-good FORMATFILE (.fmt) to confirm whether the issue lies in file-based configuration versus inline T-SQL options.