How to fix Error 4082 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: Error 4082 — Cannot Recover Session State in SQL Server 2025

Why This Error Happens

Error 4082 occurs when SQL Server’s session state manager cannot reconstruct or reattach the session context requested by a login, typically due to a mismatch between the client’s connection resiliency token and the server-side session cache. This commonly happens after an idle connection timeout, a failover event in an Always On Availability Group, or when the tempdb session state store becomes corrupted or prematurely truncated. It can also surface when Windows Server 2025’s updated TCP/IP stack drops a connection silently, leaving the SQL Server session table with a stale or orphaned entry.

Step-by-Step Resolution Guide

Step 1: Verify Connection Resiliency Settings

  • Check the client connection string for ConnectRetryCount and ConnectRetryInterval parameters; mismatched or overly aggressive retry settings can trigger premature session recovery attempts.
  • Run SELECT session_id, connect_time, login_time FROM sys.dm_exec_sessions WHERE is_user_process = 1; to confirm whether the original session still exists on the server.
  • If the session is missing entirely, the client is attempting to recover a session that SQL Server has already purged.

Step 2: Inspect and Rebuild tempdb Session State Store

  • Open SQL Server Configuration Manager and confirm tempdb data/log files are on a healthy, non-full volume (check via EXEC sp_spaceused inside tempdb).
  • Restart the SQL Server service (net stop MSSQLSERVER then net start MSSQLSERVER) to force a clean rebuild of tempdb, which clears corrupted session state entries.
  • If running a named instance, substitute MSSQLSERVER with MSSQL$<InstanceName>.

Step 3: Review Always On Availability Group Failover Logs

  • Open Failover Cluster Manager on Windows Server 2025 and check the Cluster Events log for recent automatic failovers around the error timestamp.
  • In SQL Server Management Studio, query SELECT * FROM sys.dm_hadr_availability_replica_states; to confirm the replica role is stable (not mid-transition).
  • If failovers are frequent, review the HADR_SYNC_COMMIT wait stats to rule out network latency causing session drops.

Step 4: Apply Latest Cumulative Update and Network Driver Patch

  • Navigate to Settings > Windows Update on Windows Server 2025 / Windows 11 and install any pending OS-level network stack patches.
  • Download and install the latest SQL Server 2025 Cumulative Update from the Microsoft Update Catalog, as this error has known fixes tied to session cache handling in early builds.
  • Reboot the server after patching to ensure the TCP/IP stack and SQL Server service reinitialize cleanly.

Step 5: Reset Client-Side Connection Pooling

  • In the application’s connection string, add Pooling=False temporarily to test if stale pooled connections are causing the session mismatch.
  • Clear the connection pool manually via SqlConnection.ClearAllPools() (if using .NET) or restart the application’s connection middleware/service.

Alternative or Verification Steps

  • To verify the fix, reproduce the original workload (reconnect after an idle period or trigger a test failover) and confirm no Error 4082 appears in the SQL Server Error Log (EXEC sp_readerrorlog 0, 1, 'Error: 4082').
  • If the issue persists, as a workaround, disable connection resiliency entirely (ConnectRetryCount=0) on the client to force fresh logins instead of session recovery attempts.