How to fix " The timeout period elapsed prior to obtaining a connection from the pool, pooled connections were in use and max pool size was reached"

Question

Error detail : Randomly getting Timeout expired error when using Active Directory Managed Identity authentication with a user-assigned managed identity with Microsoft.Data.SqlClient 5.1.1 library in Azure SQL DB. It’s working fine with SQL authentication.

Error :

The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached.***

Application Detail:

Frontend Application: ASP.NET MVC 6 C# ;

ORM: Entity Framework 6 ;

Database: Azure SQL DB ;

App Deployed: Azure Web APPS;

Lib Version: Microsoft.Data.SqlClient 5.1.1

Exception:

System.InvalidOperationException: Timeout expired.  The timeout period elapsed prior to obtaining a connection from the pool.  This may have occurred because all pooled connections were in use and max pool size was reached.
   at Microsoft.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   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.Data.SqlClient.SqlConnection.Open()
   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.Storage.RelationalCommand.ExecuteReader(RelationalCommandParameterObject parameterObject)
   at Microsoft.EntityFrameworkCore.Query.Internal.FromSqlQueryingEnumerable`1.Enumerator.InitializeReader(Enumerator enumerator)
   at Microsoft.EntityFrameworkCore.Query.Internal.FromSqlQueryingEnumerable`1.Enumerator.<>c.<MoveNext>b__19_0(DbContext _, Enumerator enumerator)
   at Microsoft.EntityFrameworkCore.Storage.ExecutionStrategy.<>c__DisplayClass31_0`2.<Execute>b__0(DbContext context, TState state)
   at Microsoft.EntityFrameworkCore.Storage.ExecutionStrategy.ExecuteImplementation[TState,TResult](Func`3 operation, Func`3 verifySucceeded, TState state)
   at Microsoft.EntityFrameworkCore.Storage.ExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Query.Internal.FromSqlQueryingEnumerable`1.Enumerator.MoveNext()
</Data>
        </EventData>
    </Event>
</Events>

We follow this link to implement SQL Azure AD authentication

https://learn.microsoft.com/en-us/sql/connect/ado-net/sql/azure-active-directory-authentication?view=sql-server-ver16

Connection String:

Server=tcp:**\<ServerName\>**.database.windows.net,1433;Initial Catalog=\<**DBNAME**\>;Persist Security Info=False;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=300;Min Pool Size=0;Max Pool Size=2024;Pooling=True;Authentication=Active Directory Managed Identity;User Id=\<**MI Object Id**\>

Code:

Startup code:

class Startup
{ 
    services.AddDbContext<MYDBContext>(m => m.UseSqlServer(conString, sqlServerOptionsAction: o => o.EnableRetryOnFailure()));

    services.AddTransient<IPageRepository, PageRepository>();
}

An Example for SP call:

class PageRepository
{
    public PageRepository(MYDBContext context) : base(context)
    {
        _context = context;
    }

    public Page? GetPage(string pageUrl, Guid eventId, Guid phaseId, string releaseAuthtoken = "")
    {
        string sql = "EXECUTE [Admin].[uspGetPage] @PageUrl,@EventId,@PhaseId,@ReleaseAuthtoken";
        List<SqlParameter> parms = new List<SqlParameter>()
        {
            new SqlParameter("@PageUrl",pageUrl),
            new SqlParameter("@EventId", eventId),
            new SqlParameter("@PhaseId", phaseId),
            new SqlParameter("@ReleaseAuthtoken", releaseAuthtoken),
        };
        var page = _context.Page.FromSqlRaw<Page>(sql, parms.ToArray()).AsEnumerable<Page>();

        return page.FirstOrDefault();
    }
}

I tried disabling the query tracking behaviors as we have only read operation in our Application

UseQueryTrackingBehavior(QueryTrackingBehavior.NoTracking) 

It's not working How can I solve this?