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Resolve Model database corruption in SQLLocalDB

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This article describes a known issue in the SQLLocalDB utility that can prevent the ADSync service from starting because of a corrupted Model database. This issue mainly affects Microsoft Entra Connect 2.x servers that run on a Microsoft SQL Server 2019 LocalDB.

The issue is caused by a bug in the SQL Server backup logic that creates an inconsistent state in the SQL Server Model database start page. After a backup occurs, the Model database is set to FULL recovery mode (dbi_status == 0x40010000), and the dbi_dbbackupLSN (the log sequence number (LSN) for the database backup) is set to a value that points to a log file. However, the actual recovery mode that is governed by the Master database is SIMPLE.

In SIMPLE recovery mode, database logs are truncated automatically. In FULL recovery mode, logs are truncated only after a backup. When SQLLocalDB is restarted after the log file is truncated, it detects a backup LSN that's earlier than the earliest log file. Therefore, it won't start the service.

Review the guidance in the next sections to learn how to do the following tasks:

  • Correctly identify whether the Microsoft Entra Connect service (ADSync) doesn't start because of Model database corruption.

  • Mitigate the issue by recovering the Model database from a corrupted state.

  • Apply a permanent fix to make sure that this Model database corruption doesn't occur again.

Symptoms

You can verify that the issue is based on the following events in the Microsoft Entra Connect server:

  • Event Viewer: Application, EventID 528, Source: SQLLocalDB 15.0

    WaitForMultipleObjects
575
{Application Error}
The application was unable to start correctly (0x%lx). Click OK to close the application.
3714

  • Event Viewer: Application, EventIDs 2005 and 6226, Source: ADSync

    0x8023044a
OriginalError=0x80004005 OLEDB Provider error(s):
Description  = 'Login timeout expired'
Failure Code = 0x80004005

  • SQLLocalDB error.log file in <ADSync service profile path>\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\ADSync2019

    <yyyy-MM-dd HH:mm:ss.##> spid14s     The resource database build version is 15.00.4138. This is an informational message only. No user action is required.
<yyyy-MM-dd HH:mm:ss.##> spid8s      Starting up database 'msdb'.
<yyyy-MM-dd HH:mm:ss.##> spid14s     Starting up database 'model'.
<yyyy-MM-dd HH:mm:ss.##> spid14s     Error: 9003, Severity: 20, State: 1.
<yyyy-MM-dd HH:mm:ss.##> spid14s     The log scan number (41:488:1) passed to log scan in database 'model' is not valid. This error may indicate data corruption or that the log file (.ldf) does not match the data file (.mdf). If this error occurred during replication, re-create the publication. Otherwise, restore from backup if the problem results in a failure during startup.
<yyyy-MM-dd HH:mm:ss.##> spid14s     SQL Trace was stopped due to server shutdown. Trace ID = '1'. This is an informational message only; no user action is required.

Mitigation

Important

Only apply the mitigation steps that are described here if all of these conditions occur:

  • The version of Microsoft Entra Connect is 2.0.x.x.

  • Microsoft Entra Connect is installed with SQL LocalDB.

  • All of the conditions that are listed in Symptoms are present.

To recover the Model database from a corrupted state, follow these steps:

  1. Go to one of the following ADSync Service profile locations, depending on the service account that's running (such as a domain account, virtual service account, or managed service account):

    • C:\Users\<service account>\
    • C:\Users\ADSyncMSAxxxx$\
    • C:\Windows\ServiceProfiles\ADSync\

  2. Open the error.log file from the ADSync2019 instance folder in the following directory path:

    <service profile path>\AppData\Local\Microsoft\Microsoft SQL Server Local DB\Instances\ADSync2019\

  3. Find the following error entry in the log to verify that the Model database is corrupted:

    <yyyy-MM-dd HH:mm:ss.##> spid14s     Error: 9003, Severity: 20, State: 1.
<yyyy-MM-dd HH:mm:ss.##> spid14s     The log scan number (41:488:1) passed to log scan in database 'model' is not valid. This error may indicate data corruption or that the log file (.ldf) does not match the data file (.mdf). If this error occurred during replication, re-create the publication. Otherwise, restore from backup if the problem results in a failure during startup.

  4. If error "9003" exists in this entry, rename the model.mdf and modellog.ldf files in this folder to old_model.mdf and old_modellog.ldf, respectively.

  5. Open the SQL Templates folder at C:\Program Files\Microsoft SQL Server\150\LocalDB\Binn\Templates.

  6. Copy the model.mdf and modellog.ldf files to the ADSync2019 instance folder from step 2.

  7. Start the ADSync service.

Solution

Microsoft has introduced a fix for this issue in Microsoft Entra Connect version 2.1.1.0. If the sync service (ADSync) can't be started, you need to apply the steps in the Mitigation section before you can upgrade Microsoft Entra Connect.

To prevent the corruption issues in the SQLLocalDB Model database, install the latest Microsoft Entra Connect build, which is available at Microsoft Entra Connect: Version release history.

Contact us for help

If you have questions or need help, create a support request, or ask Azure community support. You can also submit product feedback to Azure feedback community.