How to fix Error 2334 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 2334 – “Invalid Source Character”

Why This Error Happens

Error 2334 occurs when SQL Server’s parser encounters a character in a source file, script, or data stream that falls outside the expected character encoding range (typically during BCP operations, bulk inserts, or SSIS data flows). This is most commonly caused by a mismatch between the source file’s actual encoding (e.g., UTF-8 with BOM, UTF-16, or extended ASCII) and the encoding SQL Server expects for that operation. It can also result from corrupted source files, improper collation settings, or binary/null bytes accidentally embedded in a text file.

Step-by-Step Resolution Guide

Step 1: Identify the Exact Source File and Operation

  • Check the SQL Server error log or SSMS output pane to confirm which file, column, or import job triggered the error.
  • Note the exact character and hex value reported (e.g., 0x81, 0x8D are common invalid Windows-1252 bytes).
  • Open the source file in a hex editor (like HxD) to locate the offending byte offset.

Step 2: Correct the File Encoding

  • Re-save the source file using the correct encoding expected by your import method:
  • For BCP/BULK INSERT, use -c (char) or -w (wide/Unicode) flags explicitly rather than relying on defaults.
  • Example: bcp YourTable in "C:\Data\source.csv" -c -t, -S YourServer -T
  • If using UTF-8 source files, ensure SQL Server 2025 collation supports UTF-8 (e.g., Latin1_General_100_CI_AS_SC_UTF8).
  • Strip the Byte Order Mark (BOM) if present, as SQL Server’s BULK INSERT can misinterpret it depending on the DATAFILETYPE setting.

Step 3: Update the Format File or Import Definition

  • If using a .fmt format file for BCP, regenerate it against the current table schema:
  • bcp YourDatabase.dbo.YourTable format nul -c -f YourTable.fmt -S YourServer -T
  • In SSIS, set the Flat File Connection Manager’s CodePage property to match the source file (65001 for UTF-8, 1252 for Windows-1252).
  • Verify the DATAFILETYPE parameter in your BULK INSERT statement matches the file (char, native, widechar, or widenative).

Step 4: Sanitize or Filter Invalid Bytes (If Source Cannot Be Changed)

  • Use PowerShell to strip non-printable or out-of-range characters before import:
  • Get-Content "source.csv" -Encoding UTF8 | ForEach-Object { $_ -replace '[^\x09\x0A\x0D\x20-\x7E]', '' } | Set-Content "cleaned.csv"
  • Re-run the import against the cleaned file to confirm the invalid character was the root cause.

Alternative or Verification Steps

  • Run the import again with verbose logging (-e error.log flag in BCP) and confirm no further Error 2334 entries appear in the output log.
  • If the issue persists across multiple files, check the SQL Server instance’s default collation (SELECT SERVERPROPERTY('Collation')) and consider aligning it with your source data’s native encoding to prevent recurring mismatches.