Unable to connect to Aurora MySQL from ECS Fargate (transient failure exception)

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@guest

My .NET Core 3.1 app runs in a Docker container on AWS ECS with Fargate, and I couldnt connect to a new Aurora MySQL cluster via the writer endpoint. Postman calls through the load balancer threw a transient failure exception about enabling EnableRetryOnFailure in the UseMySql call. I tried the retry pattern and it still failed. Another user hit the same thing in 2024.

2026-09-23 12:02 UTC

@guest

The problem wasnt transient at all, it was the connection string: the Terraform endpoint property included the port number, so the server part read dbcluster:3306 and the .NET MySQL driver choked on it. Changing server=dbcluster:3306 to just server=dbcluster fixed the connection. If youre building the connection string from Terraform outputs for ECS/Fargate, strip the :3306 off the server value. Source: https://github.com/awslabs/rds-support-tools/issues/76

2026-09-23 12:02 UTC