This kind of issues are difficult to debug without a full working example. My suspicion is that some JSON file is not found as expected. Note that the JSON files referenced from the top-level vehicle JSON file must be provided relative to the vehicle data directory.
But all of this is not that relevant. Such an issue can *very* easily be identified by building the code in *Debug* mode and stepping through it with a debugger. Step through each subsystem constructor and ensure that the JSON file it attempts to use is what you expect. Have you done that? Radu From: [email protected] <[email protected]> On Behalf Of Emrullah Cebeci Sent: Monday, 10 November 2025 16:40 To: ProjectChrono <[email protected]> Subject: [chrono] Project Chrono 0xC0000005 Crash - Access violation on vehicle.Initialize() (Custom JSON Loading Issue) Hello, I am trying to load a custom vehicle in Project Chrono using JSON files, but I am receiving a 0xC0000005: Access violation (Null Pointer) error that I cannot solve. The program always crashes when it reaches the vehicle.Initialize(...) line. This indicates that the WheeledVehicle constructor failed, and the vehicle object is being created as a null pointer (nullptr). I believe the file references in my JSON files and my main.cpp code are correct. My JSON file structure is as follows: C:/Projects/vehicle_project/data/temp/vehicle/vehicle.json Here is the relevant section of my main.cpp: #include "chrono_vehicle/ChVehicleModelData.h" // ... other includes ... using namespace chrono; using namespace chrono::vehicle; int main() { // SetDataPath points to the 'data' directory from the file tree above const std::string vehicle_data_path = "C:/Projects/vehicle_project/data"; chrono::vehicle::SetDataPath(vehicle_data_path); // The vehicle JSON is called relative to the 'data' directory const std::string vehfile = "temp/vehicle/Vehicle.json"; WheeledVehicle vehicle(vehfile, ChContactMethod::SMC, false, false); // THE ERROR OCCURS ON THIS EXACT LINE vehicle.Initialize(ChCoordsys<>(ChVector3d(0, 0, 0.6), QuatFromAngleZ(0))); // ... (rest of the code) } I would greatly appreciate it if you could tell me what is causing this problem and how to solve it. Thank you. -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/4726cd2f-6b05-4bb9-8f99-66708abb54d5n%40googlegroups.com<https://urldefense.com/v3/__https:/groups.google.com/d/msgid/projectchrono/4726cd2f-6b05-4bb9-8f99-66708abb54d5n*40googlegroups.com?utm_medium=email&utm_source=footer__;JQ!!Mak6IKo!OuIEFyot2_gsXLCOsY0-A5jBZ-BnQCkPhaBDc-1X1EmuNBQMVr5N-wUdyLOFqpvXL7jK3LzSY-u-0jkXOC812P0s$>. -- You received this message because you are subscribed to the Google Groups "ProjectChrono" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/projectchrono/CH3PPF46CDC2185B4277224A25B35325C09A7CFA%40CH3PPF46CDC2185.namprd06.prod.outlook.com.
