Error: 3624, Severity: 20, State: 1. A system assertion check has failed - on AG Secondary RRS feed

  • Question

  • Hi All,

    we have two node AG with the following configuration 

    • SQL Version : Microsoft SQL Server 2016 (SP2) (KB4052908) - 13.0.5026.0 (X64)  
    • SQL Edition: Enterprise 
    • OS: Windows Server 2012 R2
    • AG - two node, secondary read only, asynchronous commit, file share witness


    In the secondary instance, we see the below errors plus a stack dump in the error log sporadically. 

    Error: 17066, Severity: 16, State: 1.

    SQL Server Assertion: File: <sosmemobj.cpp>, line=3099 Failed Assertion = 'x_btFree == m_btUsed'. This error may be timing-related. If the error persists after rerunning the statement, use DBCC CHECKDB to check the database for structural integrity, or restart the server to ensure in-memory data structures are not corrupted.

    Error: 3624, Severity: 20, State: 1.

    A system assertion check has failed. Check the SQL Server error log for details. Typically, an assertion failure is caused by a software bug or data corruption. To check for database corruption, consider running DBCC CHECKDB. If you agreed to send dumps to Microsoft during setup, a mini dump will be sent to Microsoft. An update might be available from Microsoft in the latest Service Pack or in a Hotfix from Technical Support.

    has anyone seen this error before? (particularly in the secondary).  

    Monday, October 21, 2019 4:21 AM

All replies

  • Hi

    These errors are SQL Server Internal and i don't think these are documented.

    Can you go through the below thread and let me know if that helps you.


    Hope this is helpful !!

    Thank you

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    Monday, October 21, 2019 1:50 PM
  • Hi Nuwan K,

    >> In the secondary instance, we see the below errors plus a stack dump in the error log sporadically.

    This issue may be fixed in cumulative update for SQL Server 2016 SP2.

    I suggest you open a case with Microsoft Supprt to get better help.

    They would be able to analyze the assertion dump and determine if the assertion dump has been fixed or if there are new fixes for this issue.

    Hope this could help you.

    Best Regards,

    Amelia Gu

    MSDN Community Support
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    Tuesday, October 22, 2019 7:33 AM
  • Hi All, 

    Thank you for the information. 


    I found the following bug that has been corrected with the Cumulative Update 4 for SQL Server 2016 SP2. Not sure if it relates to the same issue. 

    Please see the KB Article Number  4468322  (Sorry, I'm unable to put URLs  here as my account has not been verified yet)

    However, I'm going  to apply the latest Cumulative update and see if that fixes the issue. I will let you know how it goes. 

    Thursday, October 24, 2019 4:28 AM
  • As already suggested please apply latest CU and hopefully this will fix the issue. Also to rule out any possibility of data corruption causing this can you run the checkdb on secondary replica and post the output here.



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    Thursday, October 24, 2019 7:07 AM