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Unexpected 'database is locked' error. #36295

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#36657
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Unexpected 'database is locked' error.#36295
Bug
#36657
Assignees
cincuranet
Labels
area-adonet-sqlitecustomer-reportedpreview-1
Milestone
11.0.0

Description

@stefanpavlov
stefanpavlov
opened on Jun 25, 2025

Bug description

I'm getting SQLite Error 5: 'database is locked' exceptions when multiple parallel requests delete different rows of a table. The database connection is configured with a 1 day command timeout and for most of the requests this works fine and the request takes either a couple of milliseconds if the database is not in use or some amount of time if it is. See logs:

Log of successful commands

info: EfCoreSqliteDatabaseLockedRepro[0]
File e2cfbaed-0a49-49bf-9f6e-b2f2bba0ac23 deleted in 191 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File f577ff72-8e63-4825-b244-0a567d36b791 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File bba72f07-51fe-493a-984e-3cdff9dc0657 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File bcbd877d-2749-4c5c-be25-6890a2660e13 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 3b307cc2-a93b-4737-80ab-d21509efcfe3 deleted in 3 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 88d8cf6e-03ec-4fa9-b7d0-e0707b51de4d deleted in 3 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 26dea114-427b-4c80-a58d-20a48ccc20a7 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 9b5f24d3-76d4-4248-8aa6-133235ae1565 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 21d6fff2-322b-43b6-892c-dc36fc52a600 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File e7706c4d-5477-41e7-bcfa-240802eed4dd deleted in 3 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File a66d0ae6-e916-4b2c-822b-8d6285e74124 deleted in 3 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 6f4f1566-b771-45f2-ac96-22b4e5c9e49e deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 9f50b5a0-ea20-42d7-82c8-64c36311737d deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 36fa19ef-c311-4f85-8f07-6cfd8eb2cad2 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File c7ddb41d-affa-4a72-8adb-8195fe69a0cb deleted in 3 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 868acee7-2040-4d38-b0b3-cab8c898563d deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 4eeac983-7265-405b-b829-15e677b9d8a1 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 5531983c-c75b-467c-a8cd-ea72810112bd deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 0e05f8f3-27ca-4265-84b4-082ec83d4c91 deleted in 2 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 72ce4c17-69a1-4b40-bb63-3b6b7d456c68 deleted in 659 ms
info: EfCoreSqliteDatabaseLockedRepro[0]
File 3525c6d0-8c2e-434b-9227-c5c54bcd1ec3 deleted in 3 ms

A small percent of requests, however, fail with database is locked error:

Log of failed commands

fail: EfCoreSqliteDatabaseLockedRepro[0]
Failed to delete file 19b70b8d-3d21-42e4-a4b3-7afea35d5a97 in 1256 ms
Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
---> Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 5: 'database is locked'.
at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
at Microsoft.Data.Sqlite.SqliteDataRecord.Dispose()
at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
at System.Data.Common.DbDataReader.NextResultAsync(CancellationToken cancellationToken)
--- End of stack trace from previous location ---
at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Storage.RelationalDatabase.SaveChangesAsync(IList1 entries, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList`1 entriesToSave, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(StateManager stateManager, Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Program.<>c__DisplayClass0_0.<<

$>b__3>d.MoveNext() in C:\dev\personal\dotnet-playground\EfCoreSqliteDatabaseLockedRepro\Source\Program.cs:line 53

...

fail: EfCoreSqliteDatabaseLockedRepro[0]
Failed to delete file e6e39f29-df22-4500-aa7b-56bf1e59f0c0 in 7 ms
Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
---> Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 5: 'database is locked'.
at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
at Microsoft.Data.Sqlite.SqliteDataRecord.Dispose()
at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
at System.Data.Common.DbDataReader.NextResultAsync(CancellationToken cancellationToken)
--- End of stack trace from previous location ---
at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
--- End of inner exception stack trace ---
at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken) at Microsoft.EntityFrameworkCore.Storage.RelationalDatabase.SaveChangesAsync(IList1 entries, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList`1 entriesToSave, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(StateManager stateManager, Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
at Program.<>c__DisplayClass0_0.<<

$>b__3>d.MoveNext() in C:\dev\personal\dotnet-playground\EfCoreSqliteDatabaseLockedRepro\Source\Program.cs:line 53

I must be doing something wrong but I can't for the life of me figure it out.
Any help fixing this problem will be greatly appreciated.

Your code

https://github.com/stefanpavlov/EfSqliteDatabaseLockedMinRepro

Stack traces

fail: Microsoft.EntityFrameworkCore.Update[10000]
      An exception occurred in the database while saving changes for context type 'ApplicationDbContext'.
      Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
       ---> Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 5: 'database is locked'.
         at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
         at Microsoft.Data.Sqlite.SqliteDataRecord.Dispose()
         at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
         at System.Data.Common.DbDataReader.NextResultAsync(CancellationToken cancellationToken)
      --- End of stack trace from previous location ---
         at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
         --- End of inner exception stack trace ---
         at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Storage.RelationalDatabase.SaveChangesAsync(IList`1 entries, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList`1 entriesToSave, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(StateManager stateManager, Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
      Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
       ---> Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 5: 'database is locked'.
         at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)
         at Microsoft.Data.Sqlite.SqliteDataRecord.Dispose()
         at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()
         at System.Data.Common.DbDataReader.NextResultAsync(CancellationToken cancellationToken)
      --- End of stack trace from previous location ---
         at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
         --- End of inner exception stack trace ---
         at Microsoft.EntityFrameworkCore.Update.AffectedCountModificationCommandBatch.ConsumeAsync(RelationalDataReader reader, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.ExecuteAsync(IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.ExecuteAsync(IEnumerable`1 commandBatches, IRelationalConnection connection, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.Storage.RelationalDatabase.SaveChangesAsync(IList`1 entries, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(IList`1 entriesToSave, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.SaveChangesAsync(StateManager stateManager, Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)
         at Microsoft.EntityFrameworkCore.DbContext.SaveChangesAsync(Boolean acceptAllChangesOnSuccess, CancellationToken cancellationToken)

Verbose output

EF Core version

9,0,6

Database provider

Assembly Microsoft.EntityFrameworkCore.Sqlite

Target framework

.NET 9

Operating system

Windows 11

IDE

Visual Studio 2022 17.14.7

Activity

  1. stefanpavlov
    added
    customer-reported
    on Jun 25, 2025
  2. roji
    assigned
    cincuranet
    on Jun 26, 2025

  3. stefanpavlov commented on Jul 7, 2025

    @stefanpavlov
    stefanpavlov
    on Jul 7, 2025
    Author

    Any update on this?

  4. miryanat commented on Jul 17, 2025

    @miryanat
    miryanat
    on Jul 17, 2025

    @roji @cincuranet any ideas how to fix this? 🙏 our team is hitting a wall with this one

  5. meixger commented on Jul 17, 2025

    @meixger
    meixger
    on Jul 17, 2025

    https://www.sqlite.org/isolation.html:
    "There can only be a single writer at a time to an SQLite database"
    "WAL mode permits simultaneous readers and writers"

    Try using a SemaphoreSlim on your code writing to SQLite. https://github.com/meixger/EfSqliteDatabaseLockedMinRepro/commit/a34c81dcb29c48bd0043e3b781016b941738513f

    Or use a asynchronous background queue for writes. https://servicestack.net/posts/scalable-sqlite

  6. stefanpavlov commented on Jul 17, 2025

    @stefanpavlov
    stefanpavlov
    on Jul 17, 2025
    Author

    Thank you, I am well aware of SQLite's limitations and possible workarounds. There are a couple of reasons why I want this issue resolved rather than hidden under the carpet.

    1. Unless my understanding of the documentation and code (see here) is wrong, my minimal repro should not fail. The fact that some commands wait for the database to become available and others fail long before the timeout is not inspiring confidence. I'll work around this specific issue but how long until another problem pops (spoiler: it already has)?

    2. I actually have a much bigger problem with a different command which seems like it might be related to this one. A background worker queries for some condition and, if it's met, updates the database. Under certain conditions the update command gets stuck and breaking under a debugger shows it's waiting for the database to stop being busy. The catch is, there is noone else writing to the database and the problem doesn't go away even after I make sure there are no readers either. I was unable to produce a minimal repo of that problem so I was hoping this one will get resolved quickly and maybe they both have the same root cause. Here's an abridged version of the code.

    BackgroundWorker 
    public class BackgroundWorker(IServiceScopeFactory scopeFactory) : BackgroundService
{
    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        PeriodicTimer timer = new(TimeSpan.FromSeconds(15));

        while (await timer.WaitForNextTickAsync(stoppingToken))
        {
            using var scope = scopeFactory.CreateScope();
            await DoWorkAsync(scope, stoppingToken);
        }
    }

    private async Task DoWorkAsync(IServiceScope scope, CancellationToken stoppingToken)
    {
        var appDbContext = scope.Resolve<ApplicationDbContext>();

        var bucketsThatNeedArchiving = appDbContext.Buckets.TagWith("BucketsThatNeedArchiving")
            .Where(b => b.ArchiveTriggers.StagedFilesSizeExceedsBytes.Enabled && b.StagedFiles.Size >= b.ArchiveTriggers.StagedFilesSizeExceedsBytes.ValueInBytes)
            .Select(b => new { b.Id, b.Name, SizeTrigger = b.ArchiveTriggers.StagedFilesSizeExceedsBytes.ValueInBytes, b.StagedFiles});

        foreach (var bucket in bucketsThatNeedArchiving)
        {
            var newStagedFileSize = await appDbContext.Files.TagWith("GetSizeOfNewStagedFilesByBucketId")
                .Where(f => f.BucketId == bucket.Id && f.Status == FileStatus.Staged && f.JobMarker == null)
                .SumAsync(f => f.Size, stoppingToken);
            if (newStagedFileSize < bucket.SizeTrigger)
            {
                continue;
            }

            var jobMarker = Guid.NewGuid();

            var count = await appDbContext.Files.TagWith("SetFileJob")
                .Where(f => f.BucketId == bucket.Id && f.Status == FileStatus.Staged && f.JobMarker == null)
                .ExecuteUpdateAsync(f => f.SetProperty(ff => ff.JobMarker, jobMarker), stoppingToken);
        }
    }
}
  7. cincuranet
    added
    area-adonet-sqlite
    on Aug 25, 2025
  8. cincuranet
    added the
    Bug
    issue type on Aug 25, 2025
  9. cincuranet
    added a commit that references this issue on Aug 26, 2025

    Fix "IsBusy" problem when calling NextResult and disposing data record.

    fb97e41

  10. cincuranet commented on Aug 26, 2025

    @cincuranet
    cincuranet
    on Aug 26, 2025
    Contributor

    The problem is that as part of NextResult we call SqliteDataRecord.Dispose and the sqlite3_reset there can return SQLITE_BUSY. Fix in #36657. #36658 tracks bigger scope.

  11. cincuranet
    added this to the 11.0.0 milestone on Aug 26, 2025
  12. cincuranet
    linked a pull request that will close this issueFix "IsBusy" problem when calling NextResult and disposing data record. #36657on Aug 26, 2025
  13. cincuranet
    closed this as completedon Aug 28, 2025

  14. meixger commented on Aug 29, 2025

    @meixger
    meixger
    on Aug 29, 2025

    Does the 11.0.0 milestone indicate that it’s already too late for inclusion in EF Core 10?

  15. cincuranet commented on Aug 29, 2025

    @cincuranet
    cincuranet
    on Aug 29, 2025
    Contributor

    Yes. It is not going to be in 10.0, maybe servicing. For now 11 it is.

  16. roji
    added
    preview-1
    on Feb 2, 2026
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