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title MSSQLSERVER_845
description MSSQLSERVER_845
author MashaMSFT
ms.author mathoma
ms.reviewer randolphwest
ms.date 05/30/2025
ms.service sql
ms.subservice supportability
ms.topic reference
helpviewer_keywords
845 (Database Engine error)

MSSQLSERVER_845

[!INCLUDE SQL Server]

Details

Attribute Value
Product Name SQL Server
Event ID 845
Event Source MSSQLSERVER
Component SQLEngine
Symbolic Name BUFLATCH_TIMEOUT
Message Text Time-out occurred while waiting for buffer latch type %d for page %S_PGID, database ID %d.

Explanation

A process was waiting to acquire a latch, but the process waited until the time limit expired and failed to acquire one. This can occur if an I/O operation takes too long to complete, usually as a result of other tasks blocking system processes. In some instances, this error might be the result of hardware failure.

Cause

This error message is dependent on the overall environment of your system. Any of the following circumstances might lead to an overstressed system:

  • Hardware that doesn't meet your input/output (I/O) and memory needs
  • Improperly configured and tested settings
  • Inefficient design

You might observe error 845 when your system is under a heavy load and can't meet the workload demands. Some of the most common causes of a stressed environment are:

  • Hardware problems
  • Compressed volumes
  • Non-default [!INCLUDE ssNoVersion] configuration settings
  • Inefficient queries or index design
  • Frequent database autogrow or autoshrink operations

User action

Try the following to prevent this error from occurring:

  • Determine if you have any hardware bottlenecks. See Identify Bottlenecks for a good place to start. If necessary, upgrade your hardware so it can service the needs of your environment's configuration, queries, and load.

  • Verify that all your hardware functions properly. Check for any logged errors and run any diagnostics provided by your hardware vendor. Check for associated I/O failures in error log or event log. I/O failures typically point to a disk malfunction.

  • Make sure that your disk volumes aren't compressed. Storing data and log files on compressed drives isn't supported, see Database files and filegroups. For additional information on compressed drive support, review the following article: Description of support for SQL Server databases on compressed volumes

  • See if the error messages disappear when you turn off all the following [!INCLUDE ssNoVersion] configuration options:

  • Tune queries to reduce resources used on the system. Performance tuning helps reduce the stress on a system and improve response time for individual queries.

  • Set the autoshrink property to OFF to reduce the overhead of changes to your database size.

  • Make sure you set the autogrow property to increments that are large enough to be infrequent. Schedule a job to check the available space in your databases, and then increase the database size during off-peak hours.

  • Check the error log for non-yielding tasks and other critical errors. Resolve those errors first as they could point to the root cause of the underlying issue.

  • If critical errors such as asserts frequently occur, resolve these problems.

  • If the 845 error messages are infrequent, then you can ignore the errors.