What's the difference between a hang and an ANR?

An ANR (Application Not Responding) is the mobile OS's signal that an app has been unresponsive for too long, it's essentially the mobile manifestation of a hang, with the same underlying cause: a blocked main thread. So a hang is the general phenomenon (the game stuck and unresponsive while still running), and an ANR is how mobile platforms flag a hang that lasts beyond a threshold. The diagnosis and fix are the same: find and unblock the main thread.

How do I fix a game that hangs?

Identify what's blocking the main thread, a long-running operation, a deadlock, an infinite loop, or blocking I/O, and address it, usually by moving the heavy or blocking work off the main thread so it can't freeze rendering and input, or by fixing the deadlock or loop. The goal is keeping the main thread free to respond, with heavy work done in the background. Capturing context around when the game becomes unresponsive helps you locate the blocking operation.

What Causes a Game to Hang?

Q: What causes a game to hang?

A game hangs when its main thread (which handles updates, rendering, and input) is blocked and stops progressing, so the game can't respond. The usual causes are a long-running operation on the main thread (heavy computation or slow I/O), a deadlock (two operations waiting on each other), an infinite loop, blocking I/O (waiting synchronously on a slow or unresponsive resource), or a synchronous load of a large asset. The process stays alive but appears unresponsive.

Quick answer: A game hangs when it becomes unresponsive without crashing, almost always because the main thread is blocked, by a long operation, a deadlock, or an infinite loop. The process stays alive but stops progressing.

A hang, where the game becomes unresponsive but doesn't close, is closely related to a freeze and shares its causes. The game is alive but stuck. Understanding why helps you fix it. Here's what causes a game to hang.

Why the Game Stops Responding

A hang means the game's main thread, which handles updates, rendering, and input, has stopped progressing, so the game can't respond. The blocking causes are consistent.

A long-running operation on the main thread, heavy computation or slow I/O that takes too long, blocking everything until it finishes
A deadlock, two operations each waiting on the other, so neither proceeds
An infinite loop, code stuck repeating without an exit
Blocking I/O, waiting synchronously on a file, network, or resource that's slow or never responds
A synchronous load, loading a large asset or level on the main thread, hanging the game until done

While the main thread is blocked, the game appears hung, unresponsive to input, often with a frozen frame, even though the process is running.

Hangs and ANRs

On mobile, a hang that lasts long enough is surfaced by the OS as an ANR (Application Not Responding), a signal that the app hasn't responded to input for too long. So an ANR is essentially the mobile manifestation of a hang, with the same underlying cause: a blocked main thread.

Bugnet captures crashes and helps surface unresponsiveness patterns. Whether you call it a hang or an ANR, the cause is the same, the main thread can't respond, so the diagnosis and fix are the same: find and unblock the thread.

Finding and Fixing the Cause

Fixing a hang means identifying what's blocking the main thread and addressing it, usually by moving the long-running or blocking operation off the main thread, or fixing the deadlock or infinite loop. The goal is to keep the main thread free to respond, so heavy work happens in the background.

Bugnet captures context around when the game becomes unresponsive, helping you locate the blocking operation. So a game hangs because its main thread is blocked, by a long operation, deadlock, or infinite loop, and the fix is keeping that thread responsive by offloading or fixing the blocking work.

A game hangs when its main thread is blocked, by a long operation, deadlock, or infinite loop. On mobile this is flagged as an ANR. The fix is keeping the main thread responsive by offloading blocking work.