How to fix Error 5365 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 5365 – “Cyclic Window References Are Not Permitted”

Why This Error Happens

This error occurs when a T-SQL query defines a named window (using the WINDOW clause) that directly or indirectly references itself through the OVER clause chain, creating a circular dependency that SQL Server’s query optimizer cannot resolve. It typically arises from a misconfigured window alias where Window B is defined in terms of Window A, and Window A is simultaneously defined in terms of Window B. This can also surface after upgrading to SQL Server 2025 if legacy queries relied on non-standard window-chaining syntax that was previously tolerated by the parser but is now strictly validated.

Step-by-Step Resolution Guide

Step 1: Identify the Offending Query

  • Check the SQL Server error log or the client application’s exception stack trace to locate the exact query batch returning Error 5365.
  • Run the query in SQL Server Management Studio (SSMS) connected to your Windows Server 2025 instance to reproduce the error in isolation.
  • Look specifically for WINDOW clause definitions (e.g., WINDOW w AS (...)) in the query text.

Step 2: Audit the Window Definitions for Circular Logic

  • Manually trace each named window reference back to its base definition.
  • Example of a problematic pattern to search for:
  WINDOW 
      w1 AS (PARTITION BY col1 ORDER BY w2),
      w2 AS (PARTITION BY col1 ORDER BY w1)
  • Confirm no window alias refers back to itself, either directly or through a chain of two or more intermediate windows.

Step 3: Refactor the Query to Break the Cycle

  • Rewrite the query so each named window is based solely on physical columns or constants, not on other window aliases.
  • Example of a corrected definition:
  WINDOW 
      w1 AS (PARTITION BY col1 ORDER BY col2),
      w2 AS (PARTITION BY col1 ORDER BY col3)
  • If the logic truly requires sequential dependency, restructure using nested Common Table Expressions (CTEs) instead of chained window aliases.

Step 4: Update Database Compatibility Level (If Applicable)

  • If the query previously ran on an older engine, verify the database compatibility level is appropriate for SQL Server 2025 features:
  ALTER DATABASE [YourDatabaseName] SET COMPATIBILITY_LEVEL = 170;
  • Restart the SQL Server service via services.msc on Windows Server 2025 if compatibility changes require a service refresh.

Step 5: Clear Cached Execution Plans

  • Flush the plan cache to ensure SQL Server does not retry a stale, invalid plan tied to the old cyclic definition.
  DBCC FREEPROCCACHE;
  • Re-execute the corrected query to confirm a new, valid execution plan is generated.

Alternative or Verification Steps

  • Verification: Re-run the corrected query in SSMS and confirm it returns results without Error 5365; check SQL Server Profiler or Extended Events to ensure no deadlocked parser warnings appear during execution.
  • Alternative: If the application generating the query is a third-party ORM or reporting tool, update it to the latest version compatible with SQL Server 2025, as older query-generation logic may auto-construct cyclic window syntax that manual query rewriting cannot permanently fix at the source.