Error SIM Has Crashed in Assetto Corsa is one of the most annoying problems that players face, especially when using traffic mods. It occurs unexpectedly, interrupting the race, and is often accompanied by a complete freeze of the simulator or a return to the desktop. Unlike classic crashes related to graphics or physics, this error is directly related to artificial intelligence (AI) traffic, its interaction with the track and game settings.

Many people mistakenly believe that the problem lies in the hardware or drivers, but in practice in 80% of cases they are to blame conflicting mods, incorrect AI settings or corrupted traffic files. Even worse, the error can manifest itself in different ways: for some it occurs on specific tracks (for example, Nürburgring or Spa-Francorchamps), for others - with a certain number of cars on the track. In this article we will look at all possible reasons and we'll give step by step solutions, including hidden settings that are not written about in standard guides.

If you are tired of sudden crashes and want to finally enjoy racing with full traffic, read on. We won't limit ourselves to basic advice like "reinstall the game", but will dive into technical details, which will help even in the most advanced cases.

Why does the SIM Has Crashed error occur during traffic?

The main reason for the error is conflict between the simulator core and AI modulesresponsible for traffic behavior. B Assetto Corsa the system is responsible for this AIW (Artificial Intelligence Waypoints), which calculates routes, speeds and interactions of bots. When something goes wrong, the simulator cannot process the data correctly and crashes with a crash message.

The most common triggers:

  • 🚗 Too many cars on the highway (especially on difficult tracks with narrow sections).
  • 🔄 Conflicting traffic modes (for example, Traffic Mod + Custom AI Pack).
  • 📁 Damaged AIW files (waypoints, splines or configs).
  • 🎮 Incompatible physics settings (for example, enabled Realistic FFB with aggressive AI).
  • 🖥️ Lack of RAM (traffic consumes up to 2–3 GB of RAM above the basic requirements of the game).

Interestingly, the error occurs more often on mods with highly detailed cars (for example, GT3 or LMP1), since their physical models require more resources for calculations. The problem may also be related to version of the game: in Assetto Corsa Competizione similar crashes occur less frequently thanks to the optimized engine.

To pinpoint the source of the problem, check game logs (file ac_log.txt in a folder Assetto Corsa\logs). Look for lines mentioning AI, physics or memory allocation - they will indicate the specific module that caused the failure.

📊 What kind of traffic do you most often encounter errors with?
Standard game AI
Traffic Mod
Custom car packs (for example, GT3)
Mixed mods (several packs at the same time)

Checking mod compatibility: what conflicts with traffic

If the error appears after installing new mods, the first thing to do is disable all added packages and check if the problem persists. The most common conflicts are:

  • 🔧 Physics mods (for example, Real Feel Plugin or Custom FFB). They change control parameters, which can break AI calculations.
  • 🌍 Weather/time of day mods (for example, Sol or WeatherFX). Some of them interact incorrectly with traffic lighting.
  • 🚦 Track mods with custom AIW. If the track is not optimized for a large number of cars, bots will get stuck in invisible areas.
  • 🎯 Improved AI mods (for example, AI Improvement Mod). Sometimes they overload the system with calculations.

To identify the culprit, use elimination method:

  1. Remove all mods except basic traffic.
  2. Launch the game and check stability.
  3. Add one mod at a time and test after each one.

Special attention pay attention to files .ini in mod folders. For example, in Traffic Mod there is a parameter MAX_AI_CARS, which may be overestimated by default. If you have a weak PC, reduce it to 10–15 cars instead of the standard 20–30.

☑️ Checking mods for conflicts

Done: 0 / 4

AI settings in Assetto Corsa: optimized for stability

Many players don't know that Assetto Corsa yes hidden AI options, which can be configured manually. They are in the file: 

Assetto Corsa\system\cfg\assetto_corsa.ini

Open it via Notepad (or Notepad++) and find the section [AI]. Here are the key parameters to change:

Parameter Recommended value Explanation
MAX_OPPONENTS 12–16 Maximum number of opponents. Reduce if you have less than 8GB of RAM.
AI_STRENGTH 80–90 The power of AI. Values ​​above 95 may cause instability.
AI_AGGRESSION 50–70 Aggressiveness of bots. High values ​​increase the load on physics.
AI_MAX_SPEED_KMH 280–320 AI speed limit. Reduce if bots fly off the track.
AI_COLLISION_AVOIDANCE 1 (included) Disabling it can lead to crashes in collisions.

After changes, save the file and restart the game. If the error disappears, gradually increase the values to find a balance between performance and realism.

Critical detail: if you have the mod installed Content Manager, some AI settings may be overridden in its configs. Check the file Content Manager\cfg\settings.ini for the presence of duplicate parameters.

💡

Before changing configs, make a backup copy of them! It is enough to copy the files to a separate folder - this will help you quickly roll back if something goes wrong.

Updating and reinstalling: when all else fails

If the error persists even after optimizing the settings, the problem may lie in damaged game files or mods. Here's what to do:

  1. Check file integrity via Steam:
    • Open your Steam library.
    • PCM by Assetto Corsa → Properties → Local files → Integrity check....
  2. Update your mods:
    • Delete old traffic versions and download fresh ones from official sources (for example, RaceDepartment or Assetto Corsa Club).
    • Please pay attention to compatibility with your version of the game (for example, mods for v1.16 may not work in v1.18).
  • Reinstall the game with a clean profile:
    • Remove Assetto Corsa via Steam.
    • Delete the settings folder along the path Documents\Assetto Corsa.
    • Install the game again and test without mods.
    ⚠️ Attention: If you are using a pirated version of the game, the error SIM Has Crashed may be due to missing critical updates or damaged executable files. In this case, legal purchase is the only reliable solution.

    After reinstallation add mods one at a timestarting with traffic. This will help identify the conflicting pack at an early stage.

    Hardware reasons: hardware and drivers

    Although the error is most often related to software, faulty hardware or outdated drivers can also provoke it. Check the following:

    • 🖥️ RAM:
      • Run MemTest86 to check RAM for errors.
      • If you have less than 8 GB, close background programs (especially a browser with many tabs).
    • 🎮 Video card:
      • Update drivers via NVIDIA GeForce Experience or AMD Adrenalin.
      • Roll back the driver if the error appears after the update.
    • 💾 Hard drive/SSD:
      • Check disk health with the utility CrystalDiskInfo.
      • If the game is installed on HDD, move it to SSD - this will reduce delays when loading AI.

    Also worth checking component temperatures during the game. An overheated CPU or GPU can cause instability. Use HWMonitor or MSI Afterburnerto ensure that temperatures do not exceed:

    • CPU: 85–90°C
    • GPU: 80–85°C
    ⚠️ Attention: If you have a laptop with hybrid graphics (for example, Intel HD + NVIDIA), make sure the game runs on a discrete graphics card. To do this, in the NVIDIA Control Panel add ac.exe to the list of programs and select a high-performance GPU.

    Alternative Solutions: If Nothing Works

    If all the above methods did not help, try non-trivial ways, which sometimes save you in hopeless situations:

    • 🔄 Mute traffic sound:
      • In file assetto_corsa.ini find the parameter AUDIO_ENABLED and install 0.
      • Sometimes the error occurs due to a conflict between the AI and game audio streams.
    • 🌐 Use Content Manager launch with plugins disabled:
      • B Content Manager go to Settings → Plugins and disable everything except the basic ones.
      • Some plugins (eg Custom Shaders Patch) may conflict with AI.
    • 📋 Create a new profile in the game:
      • Sometimes profile settings become corrupted. Go to Documents\Assetto Corsa\cfg and rename your profile folder.
      • The next time you start the game, it will create a new profile with default settings.
    • 🛠️ Try the beta version of the game:
      • On Steam, go to Properties → Beta versions and select experimental.
      • Sometimes AI-related bugs are fixed in beta versions.

    Unique case: if the error occurs only on a specific track (for example, Nordschleife), try replacing the file .kn5 track to a version from another mod. Sometimes the problem lies in corrupted 3D environmental models that the AI cannot process correctly.

    What should I do if the error only occurs in multi-user mode?

    In this case, the problem is most likely related to data synchronization between the client and server. Try:

    • Disable traffic mods before logging into the server.
    • Reduce the number of machines displayed in the network settings (Multiplayer → Max Cars).
    • Use a VPN if the error is related to regional restrictions.

    If all else fails, contact the server administrator - they may have custom plugins installed that conflict with your client.

    FAQ: Frequently asked questions about the SIM Has Crashed error

    Is it possible to completely disable traffic to avoid the error?

    Yes, but this is a radical solution. In file assetto_corsa.ini find the parameter ENABLE_AI and install it in 0. However this will disable everyone bots, including career rivals. An alternative is to use traffic mods with a minimum number of cars (for example, 5–8).

    The error only appears on a specific machine. What's the matter?

    Most likely the problem is physical model this car. Some mods (especially custom ones) GT3 or Group C) have unoptimized files .ini, which break AI calculations. Try replacing the machine with a standard one (for example, Lotus Exige) and check stability. If the error disappears, remove the problematic mod.

    After the error, the game does not start. What to do?

    This is a sign critical file corruption. Try:

    1. Delete the folder Assetto Corsa\extension (Mod caches are stored there).
    2. Launch the game with the parameter -safe (to do this, add it in the shortcut properties after ac.exe).
    3. If it doesn't help, reinstall the game and completely delete all folders (including Documents\Assetto Corsa).
    The error only occurs when it rains. Is this fixable?

    Yes, the problem is related to weather mods, which do not interact correctly with traffic physics. Disable all weather mods (eg Sol or RainFX) and use the standard rain settings from the game. Also check that in the file assetto_corsa.ini there was a parameter WEATHER_EFFECTS=1 (not 2 or 3which include experimental effects).

    Can an antivirus block traffic and cause an error?

    Yes, some antiviruses (for example, Avast or Kaspersky) can block AI files as "suspicious". Add the game folder to your antivirus exclusions or temporarily disable protection for the test. Also check Windows firewall - it can block network interaction of traffic mods.

    💡

    In 90% of cases, the SIM Has Crashed error is not related to the hardware, but to mod conflicts or incorrect AI settings. Start by disabling all additional packs and test traffic in a “clean” game, gradually adding mods back.