How to fix Error 9637 on Windows Server 2025 / Windows 11

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Troubleshooting Guide: SQL Server Error 9637 — “The passed in serialized object is incorrectly encoded”

Why This Error Happens

This error typically occurs when SQL Server 2025 attempts to deserialize a binary object—such as a serialized execution plan, CLR type, spatial data object, or Service Broker message—that has been corrupted or truncated during storage or transmission. It can also arise from encoding mismatches when data is passed between mixed-version SQL Server instances or through improperly configured linked servers. Additionally, corrupted system catalog entries or damaged database pages storing serialized metadata can trigger this error during read operations.

Step-by-Step Resolution Guide

Step 1: Run Database Consistency Checks

  • Open SQL Server Management Studio (SSMS) and connect to the affected instance.
  • Execute DBCC CHECKDB ('YourDatabaseName') WITH NO_INFOMSGS, ALL_ERRORMSGS; to identify corruption in pages storing serialized objects.
  • Review the output for allocation or consistency errors tied to specific object IDs.

Step 2: Validate CLR and Spatial Data Objects

  • Check if the error originates from CLR integration by running SELECT * FROM sys.assemblies; to confirm assembly integrity.
  • If spatial data types (geometry/geography) are involved, validate the data using SELECT *, YourColumn.STIsValid() FROM YourTable;
  • Rebuild or re-import any assemblies/data flagged as invalid using ALTER ASSEMBLY or re-inserting clean source data.

Step 3: Inspect Service Broker and Linked Server Configurations

  • If using Service Broker, run SELECT * FROM sys.transmission_queue; to check for malformed messages stuck in the queue.
  • Clear corrupted messages using ALTER QUEUE commands or purge the transmission queue if safe to do so.
  • For linked servers, verify provider settings under Server Objects > Linked Servers > Providers in SSMS, ensuring “Enable Promotion of Distributed Transactions” and collation compatibility settings match source/target servers.

Step 4: Restore From a Known Good Backup

  • If corruption is confirmed via DBCC CHECKDB, restore the affected database or table from the most recent clean backup.
  • Use RESTORE DATABASE YourDatabaseName FROM DISK = 'D:\Backups\YourBackup.bak' WITH REPLACE;
  • Re-apply transaction logs if point-in-time recovery is required.

Alternative or Verification Steps

  • After applying fixes, re-run the original query or operation that triggered Error 9637 and confirm it completes without exceptions; also re-run DBCC CHECKDB to ensure zero allocation/consistency errors remain.
  • If the issue persists, enable SQL Server extended events (sp_configure 'show advanced options') to capture the exact serialized payload at failure time, then escalate to Microsoft Support with the captured binary dump for deeper diagnostics.