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<div class="h9">Exception Message:</div>
<pre><code>PM&gt; Update-Database
Build started...
Build succeeded.
System.InvalidOperationException: The ConnectionString property has not been initialized.
   at Microsoft.Data.SqlClient.SqlConnection.PermissionDemand()
   at Microsoft.Data.SqlClient.SqlConnectionFactory.PermissionDemand(DbConnection outerConnection)
   at Microsoft.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at Microsoft.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry, SqlConnectionOverrides overrides)
   at Microsoft.Data.SqlClient.SqlConnection.Open(SqlConnectionOverrides overrides)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerConnection.OpenDbConnection(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternal(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open(Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.&lt;&gt;c__DisplayClass18_0.&lt;Exists&gt;b__0(DateTime giveUp)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.&lt;&gt;c__DisplayClass12_0`2.&lt;Execute&gt;b__0(DbContext _, TState s)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.ExecutionStrategyExtensions.Execute[TState,TResult](IExecutionStrategy strategy, TState state, Func`2 operation, Func`2 verifySucceeded)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists(Boolean retryOnNotExists)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerDatabaseCreator.Exists()
   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.&lt;&gt;c__DisplayClass0_0.&lt;.ctor&gt;b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
The ConnectionString property has not been initialized.
</code></pre>
<div class="image-outer"><img src="https://www.learnentityframeworkcore.com/images/efcore/migrations/update-database/troubleshooting-the-connectionstring-property-has-not-been-initialized.png" loading="lazy" alt="Exception - The ConnectionString property has not been initialized"></div>
<div class="h9">Cause:</div>
<p>This error arises when EF Core fails to locate the connection string in your configuration file, resulting in an empty connection string being used.</p>
<p>In the example provided, the <code>Configuration</code> property is initialized during application startup. However, EF Core doesn't set it when using the <code>IDesignTimeDbContextFactory</code>.</p>
<pre><code class="language-csharp">namespace Z
{
    public class MyContextNameFactory : IDesignTimeDbContextFactory&lt;Z.MyContextName&gt;
    {
        public static IConfigurationRoot Configuration { get; set; }
        public Z.MyContextName CreateDbContext(string[] args)
        {
            // return an empty string as the `Configuration` property has not been correctly initialized.
            var connectionString = Configuration.GetConnectionString(&quot;DefaultConnection&quot;);

var optionsBuilder = new DbContextOptionsBuilder&lt;Z.MyContextName&gt;();
            optionsBuilder.UseSqlServer(new SqlConnection(connectionString));

return new Z.MyContextName(optionsBuilder.Options);
        }
    }
}

</code></pre>
<div class="h9">Solution:</div>
<p>To fix this, ensure the <code>Configuration</code> property is initialized the same way you typically do in your project:</p>
<pre><code class="language-csharp">namespace Z
{
    public class MyContextNameFactory : IDesignTimeDbContextFactory&lt;Z.MyContextName&gt;
    {
        public static IConfigurationRoot Configuration { get; set; }

static MyContextNameFactory() 
        {
            var builder = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile(&quot;appsettings.json&quot;, optional: true, reloadOnChange: true);

IConfigurationRoot configuration = builder.Build();
            MyContextNameFactory.Configuration = configuration;
        }

public Z.MyContextName CreateDbContext(string[] args)
        {
            var connectionString = Configuration.GetConnectionString(&quot;DefaultConnection&quot;);

var optionsBuilder = new DbContextOptionsBuilder&lt;Z.MyContextName&gt;();
            optionsBuilder.UseSqlServer(new SqlConnection(connectionString));

return new Z.MyContextName(optionsBuilder.Options);
        }
    }
}
</code></pre>
<p>Some other solution might be required depending on the scenario:</p>
<ul>
<li>Check if <code>appsettings.json</code> is copied to the output directory.</li>
<li>Verify the <code>name</code> of the connection string matches the one in <code>appsettings.json</code>.</li>
</ul>

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