How to fix Error 9975 on Windows Server 2025 / Windows 11

by

Why This Error Happens

Error 9975 occurs when a ALTER FULLTEXT INDEX ... RESUME POPULATION command is issued against a full-text catalog or index that is not currently in a paused state. SQL Server 2025 only allows the resume operation to transition a population from “paused” to “in progress”; if the population has already completed, failed, or was never paused in the first place, the command is rejected and ignored rather than throwing a hard failure. This is typically a timing/state-synchronization issue where an automation script, maintenance job, or administrator sends a resume command without first validating the current crawl status via sys.dm_fts_index_population.

Step-by-Step Resolution Guide

Step 1: Verify the Current Population Status

  • Open SQL Server Management Studio (SSMS) and connect to the target instance running on Windows Server 2025 / Windows 11.
  • Run the following query to check the live status of the population:
  SELECT table_id, population_type, status, status_description 
  FROM sys.dm_fts_index_population 
  WHERE database_id = DB_ID('YourDatabaseName');
  • Confirm whether status_description shows “Paused,” “In progress,” or “Idle.” Only “Paused” supports a resume command.

Step 2: Cancel Conflicting Automation Jobs

  • Check SQL Server Agent (via SSMS > SQL Server Agent > Jobs) for any maintenance plans scheduled to resume full-text population on a timer.
  • Disable or reschedule any job that fires RESUME POPULATION without first checking state, as overlapping job schedules are the most common cause of this warning.
  • Use sp_help_job in a query window to list active schedules tied to full-text maintenance.

Step 3: Correct the Full-Text Catalog State

  • If the population has actually finished or failed (not paused), do not issue a resume command. Instead, trigger a fresh population:
  ALTER FULLTEXT INDEX ON YourTableName START FULL POPULATION;
  • If the index appears stuck in a phantom “paused” state due to catalog corruption, rebuild the full-text catalog via:
  ALTER FULLTEXT CATALOG YourCatalogName REBUILD;
  • Ensure the SQL Server service account has read/write access to the full-text catalog folder, typically located at C:\Program Files\Microsoft SQL Server\MSSQL17.MSSQLSERVER\MSSQL\FTData\ on Windows Server 2025.

Step 4: Restart the Full-Text Filter Daemon Launcher Service

  • Open services.msc on Windows Server 2025 / Windows 11.
  • Locate SQL Full-text Filter Daemon Launcher (MSSQLSERVER) and restart it to clear any stale population locks.
  • Re-run Step 1 to confirm the status has reset to “Idle” before attempting any new population command.

Alternative or Verification Steps

  • After applying fixes, re-run the sys.dm_fts_index_population query from Step 1 — a successful fix shows status_description cycling correctly from “In progress” to “Idle” without throwing Error 9975.
  • If the warning persists, drop and recreate the full-text index entirely using DROP FULLTEXT INDEX ON YourTableName followed by CREATE FULLTEXT INDEX, which guarantees a clean population state at the cost of a full re-index.