when execute multi query on same time using threading get error 40?

I work on unity csharp . i try to execute multi query  on sql sever database using async await threading on same time but i get error

so How to solve this error please and why this error generated

SqlException: Snix_Connect (provider: SNI_PN7, error: 40 - SNI_ERROR_40)

Snix_Connect (provider: SNI_PN7, error: 40 - SNI_ERROR_40)

System.Data.SqlClient.SqlInternalConnectionTds..ctor (System.Data.ProviderBase.DbConnectionPoolIdentity identity, System.Data.SqlClient.SqlConnectionString connectionOptions, System.Object providerInfo, System.Boolean redirectedUserInstance, System.Data.SqlClient.SqlConnectionString userConnectionOptions, System.Data.SqlClient.SessionData reconnectSessionData, System.Boolean applyTransientFaultHandling) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.SqlClient.SqlConnectionFactory.CreateConnection (System.Data.Common.DbConnectionOptions options, System.Data.Common.DbConnectionPoolKey poolKey, System.Object poolGroupProviderInfo, System.Data.ProviderBase.DbConnectionPool pool, System.Data.Common.DbConnection owningConnection, System.Data.Common.DbConnectionOptions userOptions) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.ProviderBase.DbConnectionFactory.CreateNonPooledConnection (System.Data.Common.DbConnection owningConnection, System.Data.ProviderBase.DbConnectionPoolGroup poolGroup, System.Data.Common.DbConnectionOptions userOptions) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.ProviderBase.DbConnectionFactory.TryGetConnection (System.Data.Common.DbConnection owningConnection, System.Threading.Tasks.TaskCompletionSource`1[TResult] retry, System.Data.Common.DbConnectionOptions userOptions, System.Data.ProviderBase.DbConnectionInternal oldConnection, System.Data.ProviderBase.DbConnectionInternal& connection) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal (System.Data.Common.DbConnection outerConnection, System.Data.ProviderBase.DbConnectionFactory connectionFactory, System.Threading.Tasks.TaskCompletionSource`1[TResult] retry, System.Data.Common.DbConnectionOptions userOptions) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection (System.Data.Common.DbConnection outerConnection, System.Data.ProviderBase.DbConnectionFactory connectionFactory, System.Threading.Tasks.TaskCompletionSource`1[TResult] retry, System.Data.Common.DbConnectionOptions userOptions) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.SqlClient.SqlConnection.TryOpen (System.Threading.Tasks.TaskCompletionSource`1[TResult] retry) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.SqlClient.SqlConnection.Open () (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.Common.DbDataAdapter.QuietOpen (System.Data.IDbConnection connection, System.Data.ConnectionState& originalState) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.Common.DbDataAdapter.FillInternal (System.Data.DataSet dataset, System.Data.DataTable[] datatables, System.Int32 startRecord, System.Int32 maxRecords, System.String srcTable, System.Data.IDbCommand command, System.Data.CommandBehavior behavior) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.Common.DbDataAdapter.Fill (System.Data.DataTable[] dataTables, System.Int32 startRecord, System.Int32 maxRecords, System.Data.IDbCommand command, System.Data.CommandBehavior behavior) (at <290425a50ff84a639f8c060e2d4530f6>:0)

System.Data.Common.DbDataAdapter.Fill (System.Data.DataTable dataTable) (at <290425a50ff84a639f8c060e2d4530f6>:0)

(wrapper remoting-invoke-with-check) System.Data.Common.DbDataAdapter.Fill(System.Data.DataTable)

StockUpdate.ProcessUpdateTask (TextureContainer textureContainer, System.Collections.Generic.List`1[T] assignedShelfFaceDatas, Automation automation, UnionCoop.Core.data.Stock stock) (at <572a6c74c0474fd7ae89cf224552a56e>:0)

StockUpdate+<>c__DisplayClass10_4.b__6 () (at <572a6c74c0474fd7ae89cf224552a56e>:0)

System.Threading.Tasks.Task`1[TResult].InnerInvoke () (at :0)

System.Threading.Tasks.Task.Execute () (at :0)

--- End of stack trace from previous location where exception was thrown ---

System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () (at :0)

System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) (at :0)

System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) (at :0)

System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) (at :0)

System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () (at :0)

StockUpdate+d__10.MoveNext () (at <572a6c74c0474fd7ae89cf224552a56e>:0)

--- End of stack trace from previous location where exception was thrown ---

System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () (at :0)

System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess (System.Threading.Tasks.Task task) (at :0)

System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification (System.Threading.Tasks.Task task) (at :0)

System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd (System.Threading.Tasks.Task task) (at :0)

System.Runtime.CompilerServices.TaskAwaiter`1[TResult].GetResult () (at :0)

Automation+d__69.MoveNext () (at <572a6c74c0474fd7ae89cf224552a56e>:0)

--- End of stack trace from previous location where exception was thrown ---

System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw () (at :0)

System.Runtime.CompilerServices.AsyncMethodBuilderCore+<>c.b__6_0 (System.Object state) (at :0)

UnityEngine.UnitySynchronizationContext+WorkRequest.Invoke () (at <85d1d3e7744a4a47b5f51883bf40bba2>:0)

UnityEngine.UnitySynchronizationContext:ExecuteTasks()