How to fix Error 3827 on Windows Server 2025 / Windows 11

by

Troubleshooting Guide: SQL Server Error 3827 – Unavailable Table with Persisted Computed Column

Why This Error Happens

This error occurs when a persisted computed column’s underlying function or schema-bound dependency has been altered, dropped, or marked unreliable, causing SQL Server to flag the entire table as unavailable rather than risk returning stale or incorrect data. It commonly happens after a CLR assembly update, a change in a user-defined function’s determinism properties, or a collation/schema change that invalidates the persisted value’s reliability. SQL Server 2025’s stricter dependency validation engine is more aggressive about catching these inconsistencies than previous versions, so changes that previously went unnoticed now trigger this block.

Step-by-Step Resolution Guide

Step 1: Identify the Dependent Object Causing the Conflict

  • Run SELECT * FROM sys.computed_columns WHERE object_id = OBJECT_ID('YourTableName') to locate the problematic persisted column.
  • Cross-reference the column’s definition with sys.sql_expression_dependencies to find the exact function or object referenced (%.*ls in the error message).
  • Check SQL Server Error Log (C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\Log\ERRORLOG) for the full expanded error, which names the dependent function.

Step 2: Rebuild or Refresh the Computed Column Definition

  • Execute sp_refreshsqlmodule 'FunctionOrViewName' to force SQL Server to recompile the dependent object’s metadata.
  • If the underlying function was altered, temporarily drop the persisted constraint using ALTER TABLE YourTableName ALTER COLUMN ComputedColumnName DROP PERSISTED (verify no indexes depend on it first).
  • Re-add persistence with ALTER TABLE YourTableName ALTER COLUMN ComputedColumnName ADD PERSISTED once the dependency is stable.

Step 3: Validate Schema-Binding and Determinism Settings

  • Confirm the function used in the computed column is still marked SCHEMABINDING and deterministic using OBJECTPROPERTYEX(OBJECT_ID('FunctionName'), 'IsDeterministic').
  • If a CLR assembly changed, redeploy it with ALTER ASSEMBLY and ensure PERMISSION_SET matches prior configuration (SAFE, EXTERNAL_ACCESS, or UNSAFE).
  • Restart the SQL Server service via services.msc or net stop MSSQLSERVER && net start MSSQLSERVER to clear cached execution plans referencing the broken dependency.

Step 4: Rebuild Indexes on the Affected Table

  • Run ALTER INDEX ALL ON YourTableName REBUILD to ensure persisted values are recalculated cleanly post-fix.
  • Monitor for additional warnings during rebuild, as corrupted index pages can co-occur with this error.

Alternative or Verification Steps

  • Run DBCC CHECKTABLE('YourTableName') WITH ALL_ERRORMSGS to confirm the table is no longer flagged as unavailable and no corruption remains.
  • If the error persists, drop and fully recreate the computed column with ALTER TABLE ... DROP COLUMN followed by ALTER TABLE ... ADD ComputedColumnName AS (...) PERSISTED, then re-run DBCC CHECKTABLE to confirm resolution.