HeartBeat fails sometimes - SqlException

Hey!

After checking the log on my production server I’ve found some SqlExceptions which I really don’t know why they occur. SqlServer Express Core (running on Ubuntu) is definitely reachable, however the exception tells me that an error occured during the login process (this does not happen all the time).

System.Data.SqlClient.SqlException (0x80131904): A connection was successfully established with the server, but then an error occurred during the login process. (provider: TCP Provider, error: 0 - Eine vorhandene Verbindung wurde vom Remotehost geschlossen.)
 ---> System.ComponentModel.Win32Exception (10054): Eine vorhandene Verbindung wurde vom Remotehost geschlossen.
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Hangfire.SqlServer.SqlServerStorage.CreateAndOpenConnection()
   at Hangfire.SqlServer.SqlServerStorage.UseConnection[T](DbConnection dedicatedConnection, Func`2 func)
   at Hangfire.SqlServer.SqlServerStorage.UseConnection(DbConnection dedicatedConnection, Action`1 action)
   at Hangfire.Server.ServerHeartbeatProcess.Execute(BackgroundProcessContext context)

[07:23:32 ERR] Execution DelayedJobScheduler is in the Failed state now due to an exception, execution will be retried no more than in 00:00:25
System.Data.SqlClient.SqlException (0x80131904): A connection was successfully established with the server, but then an error occurred during the login process. (provider: TCP Provider, error: 0 - Eine vorhandene Verbindung wurde vom Remotehost geschlossen.)
 ---> System.ComponentModel.Win32Exception (10054): Eine vorhandene Verbindung wurde vom Remotehost geschlossen.
   at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData, Boolean applyTransientFaultHandling)
   at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
   at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
   at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
   at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
   at System.Data.SqlClient.SqlConnection.Open()
   at Hangfire.SqlServer.SqlServerStorage.CreateAndOpenConnection()
   at Hangfire.SqlServer.SqlServerConnection.AcquireLock(String resource, TimeSpan timeout)
   at Hangfire.SqlServer.SqlServerConnection.AcquireDistributedLock(String resource, TimeSpan timeout)
   at Hangfire.Server.DelayedJobScheduler.UseConnectionDistributedLock[T](JobStorage storage, Func`2 action)
   at Hangfire.Server.DelayedJobScheduler.Execute(BackgroundProcessContext context)
   at Hangfire.Server.BackgroundProcessDispatcherBuilder.ExecuteProcess(Guid executionId, Object state)
   at Hangfire.Processing.BackgroundExecution.Run(Action`2 callback, Object state)
ClientConnectionId:8de80151-2b07-4347-9b0f-d47d5c10a6ef
Error Number:10054,State:0,Class:20

I am using ASP.NET Core 5 with Hangfire.AspNetCore 1.7.20 and Hangfire.SqlServer 1.7.20.
Thanks in advance!

Best regards,
André