How to fix Error 4078 on Windows Server 2025 / Windows 11

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Why This Error Happens

This error occurs when a column referenced in a query, indexed view, computed column, or full-text/XML operation uses a collation that is incompatible with the specific SQL Server feature being invoked, such as binary (BIN2) requirements for XML indexes or system-level comparisons. It frequently surfaces after a database or server collation change, a cross-database query involving mismatched collations, or when migrating a database from an older SQL Server instance into SQL Server 2025 without aligning collation settings. The underlying cause is a structural mismatch between the column’s defined collation and the collation SQL Server expects for the operation to execute deterministically.

Step-by-Step Resolution Guide

Step 1: Identify the Affected Column and Current Collation

  • Run SELECT name, collation_name FROM sys.columns WHERE object_id = OBJECT_ID('YourTableName'); to locate the exact column referenced in the error message (match the ID returned in the error text).
  • Cross-reference the column ID using SELECT column_id, name FROM sys.columns WHERE object_id = OBJECT_ID('YourTableName'); to confirm which column triggered Error 4078.

Step 2: Determine the Required Collation for the Operation

  • Check whether the operation requires a binary collation (e.g., Latin1_General_BIN2) — this is common for XML indexes, full-text indexing, and certain indexed views in SQL Server 2025.
  • Compare the database default collation using SELECT DATABASEPROPERTYEX('YourDatabaseName', 'Collation'); against the column-level collation to spot mismatches.

Step 3: Alter the Column to Use the Correct Collation

  • Open SQL Server Management Studio (SSMS) 21 or Azure Data Studio connected to your Windows Server 2025 instance.
  • Run an ALTER statement similar to:
  ALTER TABLE YourTableName
  ALTER COLUMN YourColumnName NVARCHAR(100) COLLATE Latin1_General_BIN2;
  • Ensure no active indexes, constraints, or foreign keys reference the column before altering it; drop and recreate them afterward if necessary.

Step 4: Rebuild Dependent Objects

  • Drop and recreate any indexed views, full-text indexes, or XML indexes that depend on the altered column.
  • Use sp_refreshview 'YourViewName'; to refresh view metadata after the collation change.

Step 5: Restart the SQL Server Service (If Required)

  • Open Services.msc on Windows Server 2025 / Windows 11 and restart the SQL Server (MSSQLSERVER) service to clear cached execution plans referencing the old collation.
  • Alternatively, run DBCC FREEPROCCACHE; to force plan recompilation without a full service restart.

Alternative or Verification Steps

  • Re-run the original query or operation that triggered Error 4078; if it executes without error, the collation mismatch has been resolved.
  • If the issue persists, use sp_help 'YourTableName'; to audit all columns for collation consistency, and consider rebuilding the entire table with COLLATE DATABASE_DEFAULT applied uniformly across all character-based columns.