What is MSFS WASM, and how do you fix crashes or folder issues?
Learn what MSFS WASM does, where its files belong, and how to fix MSFS WASM crashes, bad package nesting and damaged work folders.
WASM in Microsoft Flight Simulator is the WebAssembly runtime used by many advanced add-ons to run compiled aircraft systems and gauges in a sandbox. To fix WASM crashes, update or isolate the add-on, correct its Community-package structure, then rebuild only that package’s generated work data if necessary.
What does WASM do in Microsoft Flight Simulator?
WASM lets an add-on run compiled C or C++ systems code without installing a conventional Windows executable or DLL. Complex aircraft may use it for avionics, flight-management systems, electrical logic and other functions that would be cumbersome in simpler instrument code.
The WASM runtime is built into Microsoft Flight Simulator; there is nothing separate for the user to install. WASM is not a graphics setting, an add-on format or the name of one universal folder.
Although the code runs in a controlled environment, an outdated or defective module can still freeze an instrument, prevent an aircraft loading or contribute to a crash to desktop. Incompatible dependencies and corrupted persistent data can produce similar symptoms.
Where is the MSFS WASM folder?
There is no global WASM folder into which you should copy downloaded modules. The source .wasm file belongs inside its complete add-on package, while writable data created by that module is normally stored separately.
| Location | Purpose | What to do |
|---|---|---|
Community\package-name | The manually installed add-on and its WASM source files | Check package nesting and install the complete package |
| Official or managed content storage | Simulator and in-sim library content | Repair or reinstall it through the simulator rather than editing files |
<simulator user-data>\packages\<package-name>\work | Writable data used by that package’s code | Rename only the affected package’s work folder when troubleshooting |
A normal Community package has manifest.json and layout.json directly inside its top-level package folder. A mistake we see constantly is an extra wrapper directory, producing a path such as Community\download-name\package-name\manifest.json; the simulator may then ignore the package entirely.
The exact roots vary between Microsoft Flight Simulator 2020, Microsoft Flight Simulator 2024, storefront installations and custom content locations. If the active package path is unclear, use our method for finding the Community folder used by the simulator rather than relying on a path copied from another PC.
The per-package work folder may not exist until the aircraft has been loaded, and not every add-on uses one. Never move the original .wasm file into work, and do not delete every folder named work.
How do you fix MSFS WASM crashes?
The reliable fix is to identify the affected package before deleting caches or reinstalling the whole simulator.
- Close Microsoft Flight Simulator fully. Do not move, replace or reset package files while the simulator is still running.
- Confirm that an add-on causes the crash. Use Safe Mode when it is offered, or temporarily move third-party packages out of Community. Disable managed add-ons separately through the in-sim library or content manager. If the simulator becomes stable, restore packages in small groups until the failure returns.
- Install the correct add-on build. An add-on intended for Microsoft Flight Simulator 2020 should not be assumed compatible with Microsoft Flight Simulator 2024. Remove the old package before installing its replacement so obsolete modules are not left behind, and avoid keeping duplicate versions under different folder names.
- Correct the package nesting. Open the extracted folders until you reach the directory containing
manifest.jsonandlayout.json; that directory is the one that belongs directly inside Community. - Rebuild only the affected package’s writable data. Find the matching package identifier under the simulator’s local
packagesdata, back up or rename itsworkfolder, then restart the simulator. The add-on can recreate it, although the first load may take longer. This can also reset saved aircraft state, preferences or other product data, so follow a product-specific reset procedure when one is supplied. - Check dependencies and conflicts. Install any required support package in the matching version, remove duplicate libraries, and test the base aircraft without liveries or modifications that alter its panel or systems files.
- Reinstall the affected package. For managed content, use the simulator’s own remove and reinstall controls. For a manual add-on, remove its complete package directory before extracting a clean copy.
If stock aircraft also crash with Community empty and managed add-ons disabled, WASM is unlikely to be the root cause. Work through our clean-configuration crash troubleshooting process for drivers, cache data, memory instability and background software.
How can you tell whether WASM caused the crash?
A WASM-related failure is most likely when the crash follows one particular aircraft or add-on and disappears when that package is removed. A cockpit that remains blank, hangs during initialisation or crashes at the same loading point also points towards that aircraft’s systems package, but none of these symptoms proves WASM is responsible.
On Windows, use Event Viewer to inspect the faulting module and exception code. The record may name only the simulator executable rather than the offending add-on, so compare the timestamp with controlled tests using an empty Community folder. A graphics-driver or system-library fault that persists with stock content should be treated as a general simulator or PC problem instead.
Can you fix WASM folders on Xbox or PlayStation?
No; console users cannot browse Community packages or manually rename a package’s work folder. On Xbox Series X|S and PlayStation 5, disable or remove the affected add-on through the simulator’s library or content manager, restart the console fully, then reinstall the latest compatible version.
PlayStation support applies to Microsoft Flight Simulator 2024; Microsoft Flight Simulator 2020 was never released for PlayStation. Console add-ons are managed content, so PC instructions involving AppData, Community or direct file editing do not apply.