MySQL Bugs: #119461: MySql.EntityFrameworkCore error when using Linq with .Contains in fails

Bug #119461	MySql.EntityFrameworkCore error when using Linq with .Contains in fails
Submitted:	25 Nov 2025 11:32	Modified:	27 Nov 2025 16:37
Reporter:	James Britton	Email Updates:
Status:	Open	Impact on me:	None
Category:	Connector / NET	Severity:	S2 (Serious)
Version:	10.0.0-rc	OS:	Any
Assigned to:		CPU Architecture:	Any

Description:
Been working on getting ready for .NET 10, but noticed that the 10.0.0-rc package seems to have issues when using .Where in Linq with .Contains call in predicate.

How to repeat:
1. Create an empty API project/

2. Add a BugDbContext that has a DbSet<FakeEntity> property. A fake entity should have an ID property and a name property. Register this DB context in the DI container.

4. Add a BugRepository class that consumes the BugDbContext from the DI container, and also has a public method called trigger that has the following implementation. And register it in the DI container as a scoped service.

"
public async Task Trigger()
    {
        await dbContext.FakeEntities.AddAsync(new FakeEntity { Name = "Fake Entity One" });
        await dbContext.FakeEntities.AddAsync(new FakeEntity { Name = "Fake Entity Two" });
        await dbContext.FakeEntities.AddAsync(new FakeEntity { Name = "Fake Entity Three" });
        await dbContext.FakeEntities.AddAsync(new FakeEntity { Name = "Fake Entity Four" });
        await dbContext.SaveChangesAsync();

        string[] list = ["Fake Entity One", "Fake Entity Four"];
        var result = await dbContext.FakeEntities.Where(x => list.Contains(x.Name))
            .ToListAsync();
        
        Console.WriteLine("Result of Query {Count} found", result.Count);
    }
"

5. After builder.Build a class that gets the BugRepository from the DI container and calls the method trigger. You can do this like this.

"
var service = app.Services.GetRequiredService<BugRepository>();
await service.Trigger();
"

6. now if you run this web application you should see an error like this.

"Unhandled exception. System.InvalidOperationException: Expression '@list' in the SQL tree does not have a type mapping assigned."

hi

I opened the fix PR.

https://bugs.mysql.com/bug.php?id=119338

Hi,

great, do you know if that will make it into a fixed version of the pre-release package?

And then is the release of the v10 package likely to be coming in January like previous releases?

Thankyou,
James Britton

Any progress on this? I've also encountered this error and would like a fix.

I am hitting the same wall

Bug still present with MySql.EntityFrameworkCore 10.0.1 & MySql.Data  9.7.0