Skip to the content
The Update Bureau
SQL Server 2019 CU26 SQL Server 2019 CU26 Cumulative update

KB5035123

KB5035123: Cumulative update for SQL Server 2019, CU branch, April 2024. Parallel SESSION_CONTEXT queries can return incorrect results

In short

CU26 includes 23 fixes, but parallel queries using SESSION_CONTEXT might return incorrect results or cause access violations. It also introduces a lock-escalation regression that can cause error 1204.

Does it affect you? Applies to: SQL Server 2019 instances on Windows or Linux. The package updates the SQL Server components installed on the instance.

Build
15.0.4365.2
Servicing branch
CU
Restart
Required
Review notes Additional details from the official release notes (1) Read note
  • What changes Long I/O can prevent sp_server_diagnostics from responding to the availability-group resource DLL within HealthCheckTimeout, causing unnecessary restart or failover. This fix requires trace flag 16301 to be enabled.

The official sources are linked at the end of the page.

For servers on the CU branch: they install cumulative updates, which also bring fixes beyond security. Servers on the GDR branch (security fixes only) get a separate update. Which branch am I on?

What changes

Fixes 16 changes

Backup Restore

  • A failed backup on a secondary replica in asynchronous-commit mode no longer produces a 9003 error.1
    Fixes the 9003 error, severity 20, state 1, when a backup operation fails on a secondary replica running in asynchronous-commit mode.

High Availability and Disaster Recovery

3 items
  • Automatic seeding no longer remains stuck at LIMIT_CONCURRENT_BACKUPS when there are no other active seeding, VDI, or backup threads on the instance.2
    Fixes automatic seeding remaining in LIMIT_CONCURRENT_BACKUPS after adding a database to an availability group.
  • A distributed availability group can connect to the other group's listener again after a failover in a multi-subnet configuration.3
    Fixes a temporary inability of the global primary or forwarder to connect to the other availability group's listener after the local group fails over between replicas in a multi-subnet configuration.
  • A slow I/O operation is less likely to cause an unnecessary restart or failover because the availability group health check is not answered in time.4
    Fixes sp_server_diagnostics not responding to the Always On availability group resource DLL within HealthCheckTimeout during long I/O. Trace flag 16301 must be enabled for this fix; tracing is added regardless of the flag.

Linux

  • An unreliable network connection during a backup to a network share no longer leaves the SQL Server instance unresponsive.5
    Fixes an unsuccessful backup-to-network-share status caused by an unreliable network connection, which could cause the SQL Server instance to stop responding.

Metadata

  • Secondary replicas are less likely to encounter random access violations when the primary has at least 16 processors and the secondary has fewer than 16.6
    Fixes a lock manager issue that might cause random access violations and dumps under the stated primary and secondary processor-count conditions.

Programmability

2 items
  • Issues with scalar UDF inlining are fixed.7
    Fixes scalar UDF inlining issues in SQL Server 2019 and SQL Server 2022.
  • A SQL Server assertion failure caused by an invalid comparison without a collation is fixed.8
    Fixes assertion failure 17065: Invalid comparison due to NO COLLATION.

Query Execution

  • Inserting a string representing negative zero into a decimal or numeric column no longer results in a later DBCC CHECKDB or DBCC CHECKTABLE error about an out-of-range value.9
    Fixes an issue where INSERT with CAST or CONVERT from a negative-zero string succeeds but DBCC CHECKDB or DBCC CHECKTABLE reports error 2570.

Replication

2 items
  • Creating a subscription on secondary replicas works when the distribution database is in an availability group.10
    Fixes errors from sp_addsubscription when creating a Subscriber on secondary replicas if the distribution database is in an availability group.
  • Adding a remote distributor no longer fails with error 18482 under the stated server-name and collation conditions.11
    Fixes error 18482 from sp_adddistributor when the Publisher server name contains lowercase characters and the Distributor uses a case-sensitive collation.

Search

2 items
  • The full-text automatic crawl function no longer stops working when full-text search is used.12
    Fixes an issue that might stop the full-text auto crawl function when using full-text search.
  • An overflow of word occurrence values during full-text merging is fixed.13
    Fixes an overflow issue of the word occurrence encountered during the full-text merging process.

SQL Agent

  • SQL Server Agent no longer terminates itself with Exception 5.14
    Fixes SQL Server Agent terminating with Exception 5 caught and SQLServerAgent initiating self-termination.

SQL Server Engine

  • An assertion failure that can occur with multiple nested inserts is fixed. Trace flag 7117 can mitigate the issue; turn it off after the version cleaner cleans the problematic page.15
    Fixes the assertion at setypes.cpp:1274 (!IsInRowDiff()) that might occur at FAILED_ASSERTION_42ac_sqlmin.dll!VersionRecPtr::IsNull with multiple nested inserts. Trace flag 7117 can mitigate the issue and should be turned off after the version cleaner cleans the problematic page.

Transaction Services

  • An access violation caused by a race between a database and parallel redo shutdown is fixed.16
    Fixes an access violation caused by a race between a database and a parallel redo shutdown.

New features 2 changes

Query Execution

  • A new setting lets administrators limit the memory used to handle remote procedure call parameters.17
    Adds the advanced max RPC request params (KB) option, configured with sp_configure, to limit memory allocated for handling RPC request parameters.

Search

  • The full-text filter usage event reports four additional input and output size measurements.18
    Adds min_input_size, max_input_size, min_output_size, and max_output_size fields to the sqlserver.fulltext_filter_usage Extended Event.

Improvement 1 change

Security Infrastructure

  • The number of extra user tokens created by SQL Server process views is limited when trace flag 4673 is used.19
    Limits the extra number of user tokens created by sys.sysprocesses or sys.dm_exec_requests by using trace flag 4673.

Known issues

  1. Open Affects: Everyone

    Incorrect behavior of SESSION_CONTEXT in parallel plans

    Queries that use SESSION_CONTEXT in parallel query plans might return incorrect results or trigger access violation dump files, particularly if the session is reset for reuse.20

    Workaround status No workaround yet

    Microsoft has not published a manual workaround for this issue yet. Monitor release health until a resolving update is available.

  2. Resolved Affects: Everyone Resolved by KB5039747

    Issue four: Possibility of error 1204 due to disabled lock escalation

    CU26 can disable lock escalation and cause error 1204. SQL Server 2019 CU28 (KB5039747) resolves this issue.21

    How to apply the workaround Workaround

    Uninstall CU26.21

Technical details

Data sheet · Security · Downloads · Components Click to collapse or expand

Data sheet

Released
2024-04-11
Classification
Updates
Type
Cumulative update
Servicing branch
CU
Restart
Required
Replaces
KB5033688
Replaced by
KB5037331
VersionBuildChannel
2019 15.0.4365.2 General availability

Security

No vulnerabilities are listed for this update.

Downloads (Microsoft Update Catalog)

Package 2019
878.5 MB
sqlserver2019-kb5035123-x64.exe Main update · KB5035123 SHA-1: f4c61471…698324

Sources

Updated
Cited passages from Microsoft's official notes (21)
  1. 1. FIX: "9003 error, sev 20, state 1" error when a backup operation fails on a secondary replica that is running in asynchronous-commit mode support.microsoft.com
  2. 2. Fixes an issue in which the automatic seeding operation for a database remains in LIMIT_CONCURRENT_BACKUPS after adding the database to a new availability group or an existing one created with automatic seeding support.microsoft.com
  3. 3. Fixes an issue in which the global primary or forwarder in a distributed availability group can't connect to the listener of the other availability group for a while after the local availability group fails over between replicas in multi-subnet configurations. support.microsoft.com
  4. 4. Fixes an issue in which the sp_server_diagnostics stored procedure doesn't respond to the Always On availability group (AG) resource DLL within the HealthCheckTimeout when the I/O takes a long time support.microsoft.com
  5. 5. Fixes an issue in which an unreliable network connection causes an unsuccessful status during backup to a network share, which causes the SQL Server instance to stop responding. support.microsoft.com
  6. 6. Fixes an issue in the lock manager that might cause random access violations and dumps on secondary replicas when the primary replica has 16 or more processors, and the secondary replicas have less than 16 processors. support.microsoft.com
  7. 7. FIX: Scalar UDF Inlining issues in SQL Server 2022 and 2019 (KB4538581) support.microsoft.com
  8. 8. Fixes the following SQL Server assertion failure: Error: 17065, Severity: 16, State: 1. Server Assertion: File: <FileName>, line = <LineNumber> Failed Assertion = 'false' Invalid comparison due to NO COLLATION. support.microsoft.com
  9. 9. Fixes an issue in which using the INSERT statement with the CAST or CONVERT function from a string representing negative zero to a decimal or numeric datatype succeeds support.microsoft.com
  10. 10. Fixes the following errors that you encounter when using sp_addsubscription to create the Subscriber on secondary replicas if the distribution database is in an availability group support.microsoft.com
  11. 11. Fixes an issue in which [error 18482] is caused when using sp_adddistributor to add a remote distributor if the Publisher server name contains lowercase characters and the Distributor server has the case-sensitive (_CS) collation. support.microsoft.com
  12. 12. Fixes an issue in which the full-text auto crawl function might stop working when you use full-text search. support.microsoft.com
  13. 13. Fixes an overflow issue of the word occurrence that you encounter during the full-text merging process. support.microsoft.com
  14. 14. Fixes an issue that causes the SQL Server Agent to terminate with the following error message: Exception 5 caught support.microsoft.com
  15. 15. Fixes an assertion failure (Location: setypes.cpp:1274; Expression: !IsInRowDiff()) that you might encounter at FAILED_ASSERTION_42ac_sqlmin.dll!VersionRecPtr::IsNull when you have multiple nested inserts. support.microsoft.com
  16. 16. Fixes an access violation caused by a race between a database and a parallel redo shutdown. support.microsoft.com
  17. 17. Adds a new advanced option 'max RPC request params (KB)' configured by using sp_configure to limit the maximum memory allocated for handling remote procedure call (RPC) request parameters. support.microsoft.com
  18. 18. Adds the following fields to the sqlserver.fulltext_filter_usage Extended Event (XEvent) to improve the telemetry reporting for the XEvent: - min_input_size - max_input_size - min_output_size - max_output_size support.microsoft.com
  19. 19. Limits the extra number of user tokens created by sys.sysprocesses or sys.dm_exec_requests by using trace flag 4673. support.microsoft.com
  20. 20. Queries that use the built-in SESSION_CONTEXT function might return incorrect results or trigger access violation (AV) dump files when run in parallel query plans. support.microsoft.com
  21. 21. SQL Server 2019 CU26 introduced a regression that can disable lock escalation, which causes error 1204 support.microsoft.com
Checked automatically: 8 of 8 checks passed, 21 quoted passages · compared with Microsoft's page on Oct 20, 2026
  • Quotes found in the official pages: passed
  • Numbers found in the sources: passed
  • Vulnerabilities from the dossier only: passed
  • Links to allowed domains only: passed
  • Every official change covered: passed
  • Readable plain text: passed
  • Changes confirmed by the file list: passed
  • Sources agree: passed

A second AI read the text against the sources: correctness 4/5, clarity 4/5, completeness 5/5. How we work

Published by The Update Bureau. Written with AI from Microsoft's own documents, checked by rules and a second AI. How we work · Report a mistake