An exception has been raised that is likely due to a transient failure

[kenkenken123]

The issue

This error occurs in the interval of some requests. What can I do to solve it?

Exception message:An exception has been raised that is likely due to a transient failure. Consider enabling transient error resiliency by adding 'EnableRetryOnFailure()' to the 'UseMySql' call.
   at MySqlConnector.MySqlConnection.CreateSessionAsync(ConnectionPool pool, Int32 startTickCount, Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 944
   at MySqlConnector.MySqlConnection.OpenAsync(Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 451
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenInternalAsync(Boolean errorsExpected, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Pomelo.EntityFrameworkCore.MySql.Storage.Internal.MySqlRelationalConnection.OpenAsync(CancellationToken cancellationToken, Boolean errorsExpected)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(AsyncEnumerator enumerator, CancellationToken cancellationToken)
   at Pomelo.EntityFrameworkCore.MySql.Storage.Internal.MySqlExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)

Further technical details

MySQL version: 5.7 Operating system: docker---mcr.microsoft.com/dotnet/aspnet:6.0 Pomelo.EntityFrameworkCore.MySql version: 6.0.2 Microsoft.AspNetCore.App version: 6

[mguinness]

You haven't provided enough context. Are you doing a migration, or querying or updating the db? Is there an inner exception?

[kenkenken123]

inner exception is “Connect Timeout expired.” i use contextpool ,i guess the pool is full??

[mguinness]

I suspect that you have a networking issue between your docker instance and the MySQL server.

I would suggest asking a question on Stack Overflow with your configuration for further help.

Cannot connect Asp.net Core WebApi in Docker with EFCore Mysql provider to non Docker Mysql on host server