---
title: Legend of Defenders Troubleshooting: il2cpp Error, Crashes
description: Fixes for Legend of Defenders launch errors (Failed to load il2cpp), crashes, rising memory use, music hum, a frozen captain and other launch-week bugs.
url: https://legendofdefenders.com/game/troubleshooting/
---

Problem · **launch week**

# Legend of Defenders troubleshooting
The most reported Legend of Defenders problem is the launch error **"Failed to load il2cpp"**. The developer's fix: allow the game through your firewall (or switch it off and on), then start again; if that fails, reinstall. Anything else: send a screenshot to the GM on the official Discord.
Quick answer

- il2cpp error: firewall first, reinstall second.

- Memory climbing over hours is a bug; restart and send logs.

- Frozen captain: fixed 4 November.

- Humming in the music: known, no fix yet.

## How do I fix "Failed to load il2cpp"?

- Allow Legend of Defenders through your firewall, or switch the firewall off and on, then start the game again. The developer gave this answer to the error in English and Chinese threads after the launch update.

- Still failing? Uninstall and reinstall the game.

- Still failing? Post a screenshot of the error on the official Discord for the GM, andaoKing.

## The game closes or won't launch. What next?
Run the il2cpp steps above even if you don't see that message; it is the common cause. Then send the error screen to the GM on Discord; the developer collects launch reports there. Lost progress after launch is a save issue, not a crash: see [demo saves](https://legendofdefenders.com/game/release-saves-and-platforms/#saves).

## Why does memory use keep growing?
After a few hours in the background one player found the game using more than half of 16 GB of RAM. The developer said that is not normal and asked for logs through the Discord GM. Until a fix ships, restart the game every few hours when you idle overnight.

## Why is there humming or a loud skill sound?

- A constant hum or white noise under the music: several players hear it; no fix announced.

- Moon Blade's skill sound is about twice as loud as others; the developer is looking into it.

## Why does my captain freeze at the edge of the map?
It was a bug: when the monsters around the captain were already locked by heroes, the captain treated them as dead and stood by. The developer fixed it on 4 November 2026. If you still see it, update the game.

## Which "bugs" are working as intended?

| What players saw | What it is |
| --- | --- |
| Hero slot visible but locked | Needs the quest-book task; see [locked slots](https://legendofdefenders.com/castle/hero-slots-and-quests/) |
| Fire to Sword towers all show Ice weakness | Weaknesses cycle every 20 floors; every tower has all of them |
| Orc mine diamonds/hour stop rising | Some levels add Treasure Realm chance instead |
| Mining Gem doesn't boost diamonds | A patch limited it to gold; the gem text was not updated |
| Borderless window shows the taskbar | A real bug the developer has acknowledged |

Fixed in the Day 1 Hotfix: Steam Deck saving, Rift boss names (the Fallen Angel kill message said Cyclops), misplaced Thunder and Poison Demon Lord towers, and shop bulk-buy panels.

## Legend of Defenders bug and crash questions

### How do I fix "Failed to load il2cpp" in Legend of Defenders?
The developer links it to the firewall: turn the firewall off and on (or allow the game through it) and start again. If that does not help, uninstall and reinstall the game.

### Legend of Defenders will not start. What can I do?
Check the il2cpp fix first. If the game still closes, the developer asks for a screenshot of the error on the official Discord, where the GM andaoKing collects reports.

### Why does Legend of Defenders use so much memory after hours?
It should not; the developer called RAM growth over a few hours abnormal and asked for logs. Restarting the game frees the memory until a fix ships.

### My captain stands still at the edge of the map. Is that a bug?
Yes, and it was fixed on 4 November 2026: the captain treated monsters already locked by other heroes as dead and waited.

Related: [settings](https://legendofdefenders.com/game/settings-and-controls/) · [saves and Steam Deck](https://legendofdefenders.com/game/release-saves-and-platforms/) · [patch notes](https://legendofdefenders.com/patch-notes/)