How to fix Error 1927 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: SQL Server Error 1927 – Duplicate Statistics Name Conflict

Why This Error Happens

Error 1927 occurs when SQL Server attempts to create a statistics object using a name that already exists on the target table, violating the uniqueness constraint for statistics objects within that table’s namespace. This typically happens when auto-generated statistics (prefixed with _WA_Sys_) collide with manually created statistics, or when a deployment script, ORM migration, or index-creation process runs without first checking for existing objects. It can also surface after replication, schema synchronization, or restoring a database where statistics metadata wasn’t properly reconciled.

Step-by-Step Resolution Guide

Step 1: Identify the Conflicting Statistics Object

  • Query sys.stats to find the existing statistics entry causing the conflict:
  SELECT s.name, s.stats_id, o.name AS table_name
  FROM sys.stats s
  JOIN sys.objects o ON s.object_id = o.object_id
  WHERE o.name = 'YourTableName';
  • Confirm the exact name and whether it was auto-created or user-defined using the auto_created column.

Step 2: Decide Whether to Drop or Rename

  • If the existing statistics are redundant or outdated, drop them:
  DROP STATISTICS YourTableName.StatName;
  • If the statistics are required (e.g., tied to a specific index or query plan), rename your new statistics object instead of overwriting the existing one:
  CREATE STATISTICS NewStatName ON YourTableName(ColumnName);

Step 3: Update Deployment or Migration Scripts

  • Modify scripts (SSDT, Flyway, Liquibase, or custom T-SQL) to include existence checks before creation:
  IF NOT EXISTS (SELECT 1 FROM sys.stats WHERE name = 'StatName' AND object_id = OBJECT_ID('YourTableName'))
  BEGIN
      CREATE STATISTICS StatName ON YourTableName(ColumnName);
  END
  • Ensure this logic is applied consistently across environments (Dev, QA, Production) on Windows Server 2025 to prevent recurrence.

Step 4: Rebuild Statistics Cleanly if Corruption Is Suspected

  • If metadata appears inconsistent after a restore or replication event, run:
  EXEC sp_updatestats;
  • For severe corruption, consider dropping and recreating all statistics on the affected table using sp_helpstats combined with scripted DROP/CREATE statements.

Alternative or Verification Steps

  • Re-run the original script or deployment pipeline after applying the fix; the CREATE STATISTICS command should complete without raising Error 1927.
  • As a verification check, query sys.stats again post-fix to confirm only the intended statistics object exists and that auto-generated stats haven’t silently reappeared with the same name due to auto-stats being enabled (ANSI_AUTO_CREATE_STATISTICS).