How do you prevent a stale network result from updating a widget after it has gone?

Short answer

Tie the operation to the owner's lifetime, cancel the subscription or use cancellation support, and check mounted before setState after an await.

Explanation

Real cancellation depends on the client; if unavailable, ignore the result after dispose and prevent races through a request id or a controller. Do not assume Future.timeout automatically cancels the work already on the network.

Common mistakes

• Calling setState after dispose.
• Treating a timeout as cancellation of the socket or server request.

Follow-up questions

• How do you use Future.wait safely with more than one async operation?

Sources

• Flutter API — State lifecycle