Fix the FSX “memory could not be read” error by finding the faulting module, resetting configuration files and isolating faulty add-ons.
The “memory could not be read” message in FSX is usually an access violation: FSX or an add-on tried to use an invalid memory address. It does not automatically mean bad RAM or exhausted memory. Test a stock flight, identify the faulting module, reset FSX’s configuration, then isolate aircraft, gauges, scenery and external modules.
Is this the same as the FSX out-of-memory error?
No. “The memory could not be read” normally indicates invalid memory access, often recorded by Windows as exception 0xc0000005. A true out-of-memory failure means 32-bit FSX has exhausted its usable virtual address space.
If the crash occurs late in a flight around dense scenery, complex aircraft or heavy AI traffic, memory pressure may still be contributing. Use our FSX virtual-memory and out-of-memory troubleshooting steps when the simulator explicitly reports insufficient memory or its memory use climbs steadily before the crash.
How can I identify what is crashing FSX?
The faulting module and the point at which FSX fails are the most useful clues. Open Windows Reliability Monitor, or check Windows Logs > Application in Event Viewer, and inspect the Application Error recorded at the crash time.
| When FSX fails | Likely area | First test |
|---|---|---|
| Before the opening screen | Configuration, startup module or saved default flight | Reset fsx.cfg and disable dll.xml/exe.xml |
| After selecting one aircraft | Aircraft model, panel or gauge | Load a stock FSX aircraft |
| At one airport or partway through loading | Add-on scenery, terrain or AI traffic | Disable the affected scenery and nearby add-on layers |
| While opening menus | UIAutomation or an in-process module | Check the module named in the Windows error record |
| After a long, demanding flight | Virtual-address exhaustion or an add-on memory leak | Repeat with simpler scenery, aircraft and traffic |
A clearly named third-party DLL usually identifies the add-on to disable or reinstall. Entries such as ntdll.dll, KERNELBASE.dll or g3d.dll often show where Windows detected the crash rather than what originally caused it. Do not download replacement copies of those DLLs from a DLL library.
How do I fix the FSX memory read error?
Work from a stock FSX flight and reintroduce each component separately. This is faster and more reliable than reinstalling everything at once.
- Test a clean flight. Start FSX or FSX: Steam Edition from Free Flight rather than loading the previous saved flight. Choose a default aircraft, a default airport, clear weather and minimal AI traffic. If this works, the base simulator is probably intact and the fault is tied to the original aircraft, location or utility.
- Record the faulting module. Reproduce the error once, note the exact time, then inspect Reliability Monitor or Event Viewer. Keep the module name and exception code; the wording in the pop-up alone is not enough to identify the cause.
- Generate a fresh
fsx.cfg. Close FSX and rename the existing file tofsx.cfg.old. Boxed FSX normally stores it beneath%APPDATA%\Microsoft\FSX. Steam Edition may use anFSXorFSX-SEfolder depending on the installation history, so inspect both. FSX creates a clean file when it next starts. - Disable startup modules. In the same configuration folder, back up and temporarily rename
dll.xmlandexe.xmlif they exist. If FSX then works, restore the files and disable their add-on entries one at a time until the failing module is found. - Isolate recently installed content. Remove or reinstall the suspect aircraft, disable recent scenery through the Scenery Library, and test without third-party AI traffic. Do not move or delete default FSX folders. An airport-specific crash can also come from an overlapping scenery layer or an AI traffic file used only in that region.
- Close external utilities. Test without weather engines, traffic injectors, recording tools, overlays and other programs connected to FSX. Re-enable one utility per test rather than starting all of them together.
- Repair the simulator files. For Steam Edition, use Steam’s Verify integrity command from the game’s Properties. For boxed FSX, use the repair option from the original media. Verification repairs standard files but may leave third-party DLLs and user configuration files untouched, which is why add-on isolation comes first.
- Repair required components only when indicated. If the log points towards a runtime or SimConnect component, use the official prerequisite installers supplied with FSX, Steam or the affected add-on. Avoid loose DLL downloads and blanket registry cleaners.
After each change, repeat the same test flight. Changing the aircraft, airport, weather and configuration simultaneously may hide the error without revealing which component caused it.
What if the error happens only in one situation?
A repeatable trigger usually identifies the faulty content more accurately than the memory message itself.
Only one aircraft causes the error
The aircraft package or one of its gauges is the leading suspect. Confirm that a default FSX aircraft works at the same airport, then reinstall the affected aircraft and any components supplied by its installer. Check that the package was made for FSX rather than relying on an incompatible gauge from another simulator.
Only one airport causes the error
The affected airport, a nearby scenery layer or regional AI traffic is probably involved. Disable the airport add-on first, followed by overlapping terrain, mesh or object-library layers. If the crash disappears, restore those layers one at a time and rebuild the scenery database when FSX requests it.
Opening menus causes the crash
Menu-triggered failures need separate treatment from aircraft or scenery crashes. If Windows names UIAutomationCore.dll, follow our specific checks for FSX menu and UIAutomationCore crashes rather than applying memory tweaks.
When should I suspect faulty RAM?
Suspect hardware only when memory errors also affect other programs, Windows reports corrupted files, or the PC produces blue screens and unexplained restarts. Return CPU, GPU and RAM overclocks to standard settings and run Windows Memory Diagnostic before replacing hardware.
Keep the Windows paging file enabled and system-managed while testing. Increasing it will not repair an invalid-pointer crash, and adding physical RAM does not remove FSX’s 32-bit address-space limit.
What if stock FSX still shows the error?
If a default flight still fails with a fresh configuration and no add-on modules, the next suspects are damaged simulator prerequisites, graphics drivers or Windows compatibility settings. Our FSX checks for Windows 10 and 11 cover legacy DirectX components, permissions and compatibility changes without assuming every crash has the same cause.
When the message varies or no consistent module appears, use the wider FSX crash-isolation checklist. Reinstallation should be the last step because uninstalling the base simulator can leave the faulty add-on file or AppData configuration behind.