異常信息：

An unhandled exception was thrown by the application.
System.ObjectDisposedException: Cannot access a disposed object. A common cause of this error is disposing a context that was resolved from dependency injection and then later trying to use the same context instance elsewhere in your application. This may occur if you are calling Dispose() on the context, or wrapping the context in a using statement. If you are using dependency injection, you should let the dependency injection container take care of disposing context instances.

遇到這種情況一般是異步、同步混著調用了。

檢查一下調用的地方是否為同步，但在實現函數裏用異步得寫法了。

Cannot access a disposed object. A common cause of this error is disposing