Entity Framework Core: How to Resolve the 'A Second Operation Started on This Context' Error?

Entity Framework Core: Resolving "A Second Operation Started on This Context" Error

When working with Entity Framework Core, developers may encounter the following error:

InvalidOperationException: A second operation started on this context before a previous operation completed. Any instance members are not guaranteed to be thread safe.

This error indicates that multiple database operations are being performed concurrently on the same context instance.

Causes and Resolution

1. Dependency Injection Configuration

Ensure that your DbContext is registered as Transient instead of Scoped. This ensures that each request or operation gets its own instance of the context, preventing thread conflicts. Use:

services.AddTransient<MyContext>();

2. Asynchronous Operations

Async lambda expressions can trigger this error. Avoid using them when querying or updating data.

3. Thread Safety Considerations

DbContext is not thread-safe. Avoid using the same context instance across multiple threads or classes.

Additional Considerations

• Hanging background jobs (e.g., Hangfire) can also contribute to this error if they use the same context.
• Extending the length of model properties can affect the behavior of the DbContext.

The above is the detailed content of Entity Framework Core: How to Resolve the 'A Second Operation Started on This Context' Error?. For more information, please follow other related articles on the PHP Chinese website!