Home Fail: Microsoft.EntityFrameworkCore.Database.Connection[20004] – Using MySql

Questions

Fail: Microsoft.EntityFrameworkCore.Database.Connection[20004] – Using MySql

July 24, 2023

I am attempting to run the command Update-Database.

I am using MySql, and have the two needed dependencies installed.

MySqlConnector

MEDevel.com: Open-source for Healthcare and Education

Collecting and validating open-source software for healthcare, education, enterprise, development, medical imaging, medical records, and digital pathology.
Visit Medevel

and

Pomelo.EntityFrameworkCore.MySql

However, when I run the command Update-Database I get the following error in the Package Manager Console:

fail: Microsoft.EntityFrameworkCore.Database.Connection[20004]
      An error occurred using the connection to database 'mydb' on server 'localhost'.
An error occurred using the connection to database 'mydb' on server 'localhost'.
System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'MySqlConnection'.
   at MySqlConnector.MySqlConnection.VerifyNotDisposed() in /_/src/MySqlConnector/MySqlConnection.cs:line 1002
   at MySqlConnector.MySqlConnection.OpenAsync(Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 388
   at MySqlConnector.MySqlConnection.Open() in /_/src/MySqlConnector/MySqlConnection.cs:line 382
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenDbConnection(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternal(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
   at Pomelo.EntityFrameworkCore.MySql.Storage.Internal.MySqlRelationalConnection.Open(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteScalar(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists()
   at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.UpdateDatabase(String targetMigration, String connectionString, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabaseImpl(String targetMigration, String connectionString, String contextType)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.UpdateDatabase.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Cannot access a disposed object.
Object name: 'MySqlConnection'.

My relevant code:

using var connectionString = new MySqlConnection(builder.Configuration.GetConnectionString("DefaultConnection"));
var serverVersion = new MySqlServerVersion(new Version(8, 0, 31));


builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseMySql(connectionString, serverVersion));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();


builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();

My connection string:

"DefaultConnection": "server=localhost;port=3306;User ID=root;Password=password;Database=mydb"

I have tried various solutions listed on here, and elsewhere, with no success.

I am not using Docker.

I am using ASP.NET 7.0

I have written a small test, and have retrieved some data from the DB.

>Solution :

You are declaring your connectionString with using var.

So when this piece of code

using var connectionString = new MySqlConnection(builder.Configuration.GetConnectionString("DefaultConnection"));
var serverVersion = new MySqlServerVersion(new Version(8, 0, 31));


builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseMySql(connectionString, serverVersion));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();


builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();

goes out of scope, your connectionString is disposed and you get System.ObjectDisposedException whenever you try to access the database outside of this scope.