FreeCAD Crash During Subtractive Cone Operation Troubleshooting Guide

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Introduction

This comprehensive article delves into a specific issue encountered in FreeCAD a crash occurring during a subtractive cone operation. We will explore the intricacies of the problem providing a detailed analysis of the crash report the FreeCAD version information and the steps taken to troubleshoot and identify potential solutions. This article aims to offer valuable insights for both novice and experienced FreeCAD users helping them understand the underlying causes of such crashes and how to effectively address them. By examining the technical aspects of the crash and providing practical workarounds we aim to enhance the FreeCAD user experience and contribute to the robustness of the software.

Understanding the Problem

The core issue at hand is a crash experienced while attempting a subtractive cone operation within the Part Design workbench in FreeCAD. This problem arose while the user was experimenting with the ThreadProfile workbench an add-on designed for creating screw threads. The user selected a circle sketch within a body and then initiated a subtractive cone operation which immediately resulted in a crash. This type of crash a segmentation fault indicates a serious problem often related to memory access or internal errors within the software. Understanding the context and the specific steps leading to the crash is crucial for effective troubleshooting and resolution. The following sections will dissect this problem providing a detailed analysis of the circumstances the error messages and the potential causes.

Detailed Problem Description

In this section, we will provide a detailed problem description to fully grasp the issue. The user was working within FreeCAD, specifically utilizing the ThreadProfile workbench, which is an add-on for generating thread profiles. The workflow involved selecting a circle sketch within a body and then attempting to perform a subtractive cone operation using the Part Design workbench. A subtractive cone operation is a Boolean operation that removes the volume of a cone from a solid body effectively cutting away material. However, upon initiating this operation FreeCAD crashed instantly. This immediate crash suggests a critical error occurring during the initial stages of the operation. The user has helpfully provided the FreeCAD project file (crash.FCStd.zip) which allows for direct examination of the design and replication of the error. Additionally, the console output provides valuable clues by showing the sequence of function calls leading up to the crash. This information is essential for developers and advanced users to diagnose the root cause of the problem which may stem from issues in the geometry the interaction between workbenches or underlying FreeCAD libraries. We will explore these aspects further in the subsequent sections.

Analyzing the Crash Report

Analyzing the crash report is a pivotal step in diagnosing the issue. The console output provided in the report reveals a segmentation fault (SIGSEGV) which is a common indicator of memory-related problems. Specifically, the crash occurs within the libc.so.6 library a core component of the Linux operating system which handles memory management. The stack trace provides a detailed sequence of function calls leading up to the crash. This trace points to the BOPDS_DS::ShapeInfo(int) const function within the libTKBO.so.7.8 library. libTKBO is part of the Open Cascade Technology (OCC) library which FreeCAD uses for its geometric modeling capabilities. The subsequent function calls such as BOPDS_DS::Shape(int) const and BOPDS_DS::IsValidShrunkData(opencascade::handle<BOPDS_PaveBlock> const&) suggest that the crash is related to Boolean operations specifically within the BOPAlgo_PaveFiller class. This class is responsible for handling the paving and filling algorithms used in Boolean operations like subtraction. The stack trace further indicates that the error arises during the IntersectShapes function within the BRepAlgoAPI_BuilderAlgo class which is used to compute the intersection of shapes. The Part::TopoShape::makeElementBoolean function call confirms that the crash occurs during a Boolean operation initiated from the Part workbench. Understanding these details is crucial for pinpointing the exact location of the bug and devising an appropriate solution. In the following sections, we will delve deeper into these technical aspects and explore potential causes.

Version Information and Its Significance

The version information provided in the crash report is crucial for understanding the context of the issue. The user was running FreeCAD version 1.1.0dev.42474 (Git) AppImage which is a development build. Development builds often contain the latest features and bug fixes but may also include new bugs that have not yet been fully resolved. The build date of 2025/07/04 indicates a relatively recent version suggesting that the bug may be newly introduced. The Git hash 927d302401caad6a9e518584e0665ae9f61509f2 uniquely identifies the specific commit in the FreeCAD source code that was used to create this build. This information is invaluable for developers to track down the exact changes that may have caused the issue. The report also specifies that the user is running Python 3.11.13 Qt 6.8.3 Coin 4.0.3 Vtk 9.3.1 and other relevant libraries. These libraries are essential dependencies for FreeCAD and compatibility issues between them can sometimes lead to crashes. The OCC version is 7.8.1 which is a significant detail as it is the geometric modeling kernel used by FreeCAD. Bugs within OCC can manifest as crashes during geometric operations. Finally, the installed mods include ThreadProfile 1.96.0 which is directly related to the user's workflow when the crash occurred. Knowing the version of this add-on is important as it helps determine if the issue is specific to this version or if it has been addressed in later updates. In summary, the version information provides a comprehensive snapshot of the software environment in which the crash occurred enabling developers and advanced users to narrow down the potential causes.

The Role of the ThreadProfile Workbench

The ThreadProfile workbench plays a significant role in the context of this crash. As an add-on designed for creating screw threads it introduces specialized geometric operations and algorithms that may interact with FreeCAD's core functionalities in unique ways. The user's workflow involved selecting a circle sketch likely created within the ThreadProfile workbench and then attempting a subtractive cone operation using the Part Design workbench. This interaction between workbenches highlights the potential for conflicts or unexpected behavior. Add-ons like ThreadProfile often rely on FreeCAD's API (Application Programming Interface) to extend its capabilities. If the add-on's code contains bugs or if it interacts with FreeCAD's internal functions in a way that was not fully anticipated it can lead to crashes. In this specific case the fact that the crash occurred during a Boolean operation a fundamental geometric operation suggests that the issue may be related to how ThreadProfile creates or manipulates geometric shapes. It is possible that the shapes generated by ThreadProfile contain geometric complexities or inconsistencies that trigger a bug in FreeCAD's Boolean operation algorithms. Therefore, understanding the internal workings of ThreadProfile and how it interacts with FreeCAD's geometry kernel is crucial for diagnosing this crash. In subsequent sections, we will explore the subtractive cone operation in more detail and investigate how it may be influenced by the shapes created by ThreadProfile.

Subtractive Cone Operation in Part Design

The subtractive cone operation within the Part Design workbench is a fundamental Boolean operation used to remove material from a solid body. It involves subtracting the volume of a cone from the existing solid resulting in a modified shape. This operation is commonly used in CAD modeling to create holes recesses or other features that require material removal. The process typically involves selecting a base solid and then creating a cone-shaped feature which is then subtracted from the base solid. The success of this operation depends on the geometric validity of both the base solid and the cone as well as the accuracy of the Boolean operation algorithms. When a subtractive cone operation fails it can be due to various reasons including geometric inconsistencies self-intersections or numerical precision issues. In the context of this crash the fact that the operation immediately causes a segmentation fault suggests a more severe problem than a simple geometric error. Segmentation faults often indicate memory access violations or internal errors in the software's code. Given that the crash occurs during the Boolean operation it is likely that the issue is related to how FreeCAD's geometric kernel Open Cascade Technology (OCC) handles the subtraction of the cone from the base solid. This could involve problems with the internal data structures used to represent the shapes or with the algorithms used to compute the Boolean operation. Understanding the technical details of the subtractive cone operation and its implementation within FreeCAD is essential for pinpointing the root cause of the crash. In the following sections, we will delve into the technical aspects of this operation and explore potential issues within the OCC library.

Technical Deep Dive

This section provides a technical deep dive into the crash, examining the underlying mechanisms and potential causes. The crash report points to a segmentation fault within the Open Cascade Technology (OCC) library, specifically in the BOPDS_DS::ShapeInfo(int) const function. OCC is the geometric modeling kernel that FreeCAD uses, and segmentation faults within OCC typically indicate memory access violations or internal errors in the geometric algorithms. The BOPDS_DS namespace suggests that the issue is related to Boolean operations, which involve complex geometric computations. The stack trace further implicates the BOPAlgo_PaveFiller class, which is responsible for handling the paving and filling algorithms used in Boolean operations. These algorithms are crucial for ensuring the accuracy and robustness of Boolean operations, especially when dealing with complex shapes. The ForceInterfEF and PutSEInOtherFaces functions within BOPAlgo_PaveFiller suggest that the crash may occur during the intersection and face processing stages of the Boolean operation. The call to BRepAlgoAPI_BooleanOperation::Build confirms that the crash happens within the Boolean operation building process. This process involves several steps, including shape intersection, face splitting, and edge welding. A failure at any of these steps can lead to a crash. The Part::TopoShape::makeElementBoolean function indicates that the operation is initiated from the Part workbench, which provides the basic geometric primitives and operations in FreeCAD. The PartDesign::FeaturePrimitive::execute and PartDesign::Cone::execute functions show that the crash occurs during the execution of a cone-related feature primitive within the Part Design workbench. This suggests that the issue may be specific to the interaction between the cone feature and the Boolean operation. To fully understand the crash, it is necessary to examine the geometric data and the specific parameters used in the subtractive cone operation. This involves analyzing the input shapes, the cone's dimensions, and the Boolean operation settings. It is also important to consider the complexity of the shapes involved, as complex geometries can sometimes trigger bugs in the Boolean operation algorithms. In the following sections, we will explore potential causes and troubleshooting steps in more detail.

Troubleshooting Steps

When encountering a crash like this, systematic troubleshooting steps are essential to identify the root cause and find a solution. Here are several steps that can be taken:

  1. Reproduce the Error: The first step is to try to reproduce the crash consistently. This involves repeating the exact steps that led to the crash, such as selecting the circle sketch and initiating the subtractive cone operation. If the crash can be reproduced reliably, it indicates a deterministic bug that can be investigated further.
  2. Simplify the Design: Complex designs can sometimes trigger bugs in geometric algorithms. Try simplifying the design by removing non-essential features or reducing the complexity of the shapes involved. This can help isolate the issue and determine if it is related to a specific geometric element.
  3. Check for Sketch Issues: Sketch-related issues, such as self-intersections or geometric constraints, can sometimes cause crashes during Boolean operations. Examine the circle sketch and ensure that it is valid and does not contain any errors. Try recreating the sketch from scratch to eliminate potential sketch-related problems.
  4. Isolate the Operation: Try performing the subtractive cone operation on a simpler base solid to see if the crash still occurs. This can help determine if the issue is specific to the interaction between the cone and the original base solid.
  5. Update FreeCAD: If you are using an older version of FreeCAD, consider updating to the latest stable release or a more recent development build. Newer versions often include bug fixes and improvements that may address the crash.
  6. Disable Add-ons: Add-ons can sometimes introduce conflicts or bugs that cause crashes. Try disabling the ThreadProfile workbench and other add-ons to see if the crash still occurs. If disabling add-ons resolves the issue, it indicates that one of the add-ons is the likely cause.
  7. Check System Resources: Insufficient system resources, such as RAM or CPU, can sometimes lead to crashes. Ensure that your system meets the minimum requirements for running FreeCAD and that there are no resource bottlenecks.
  8. Examine the FreeCAD File: The FreeCAD file (crash.FCStd) contains valuable information about the design and the operations performed. Open the file and examine the model history, feature parameters, and sketch constraints. Look for any unusual or problematic elements that may be contributing to the crash.
  9. Consult the FreeCAD Community: The FreeCAD community is a valuable resource for troubleshooting issues. Post your problem on the FreeCAD forum or other online platforms, providing as much detail as possible, including the crash report, FreeCAD version information, and a description of the steps taken to reproduce the crash. Other users may have encountered similar issues and can offer helpful advice or solutions.
  10. Report the Bug: If you have identified a bug in FreeCAD, report it to the FreeCAD developers. This helps ensure that the bug is addressed in future releases. Include the crash report, the FreeCAD file, and a clear description of the steps to reproduce the crash. This will allow developers to effectively diagnose and fix the issue.

By following these troubleshooting steps, users can systematically investigate crashes in FreeCAD and identify potential solutions. In the following sections, we will delve deeper into specific causes and workarounds.

Identifying Potential Causes

Identifying potential causes of the crash is a critical step in finding a solution. Based on the crash report and the troubleshooting steps, several factors may be contributing to the issue:

  1. Geometric Complexity: The shapes involved in the subtractive cone operation may be geometrically complex, leading to issues in the Boolean operation algorithms. Complex shapes can introduce numerical precision problems and increase the computational burden of the Boolean operation. If the shapes have many faces, edges, or vertices, the Boolean operation algorithms may struggle to compute the intersections and differences accurately.
  2. Sketch Issues: Problems within the circle sketch, such as self-intersections, overlapping elements, or invalid constraints, can lead to crashes during Boolean operations. FreeCAD relies on accurate and well-defined sketches for creating solid bodies. If a sketch contains errors, it can propagate to the resulting solid and cause issues during subsequent operations.
  3. Boolean Operation Bugs: The Boolean operation algorithms in Open Cascade Technology (OCC) may contain bugs that are triggered by specific geometric configurations. While OCC is a robust geometric modeling kernel, it is not immune to bugs. Certain geometric situations, such as nearly coplanar faces or tangential edges, can expose weaknesses in the Boolean operation algorithms.
  4. ThreadProfile Add-on: The ThreadProfile add-on may be introducing geometric elements or operations that are incompatible with FreeCAD's core functionalities. Add-ons can sometimes interact with FreeCAD in unexpected ways, leading to crashes. If the ThreadProfile add-on creates shapes with specific characteristics or uses particular algorithms, it may trigger bugs in the Boolean operation.
  5. Memory Management Issues: FreeCAD may be encountering memory management issues, such as memory leaks or buffer overflows, which can lead to segmentation faults. Segmentation faults often indicate that the program is trying to access memory that it does not have permission to access. This can be caused by programming errors in FreeCAD or in the underlying libraries.
  6. Version Incompatibilities: Incompatibilities between FreeCAD, OCC, Python, Qt, or other libraries can lead to crashes. FreeCAD relies on a complex ecosystem of software components, and version mismatches between these components can cause unexpected behavior. If the versions of the libraries are not properly aligned, it can lead to crashes.
  7. Hardware Issues: While less likely, hardware issues, such as faulty RAM or a failing CPU, can sometimes cause crashes. Hardware problems can manifest as seemingly random crashes or errors. If hardware issues are suspected, it is important to run diagnostic tests to identify any problems.

By considering these potential causes, users can focus their troubleshooting efforts and identify the most likely source of the crash. In the following sections, we will delve deeper into specific causes, such as memory management issues and the role of Open Cascade Technology (OCC).

Memory Management Issues

Memory management issues are a common cause of crashes in software applications, including FreeCAD. These issues can manifest in various forms, such as memory leaks, buffer overflows, and segmentation faults. Understanding how these issues arise and how they can impact FreeCAD is crucial for troubleshooting crashes.

  1. Memory Leaks: A memory leak occurs when a program allocates memory but fails to release it when it is no longer needed. Over time, these memory leaks can accumulate, consuming system resources and eventually leading to a crash. In FreeCAD, memory leaks can occur in various parts of the code, such as the geometric modeling kernel, the GUI, or the Python scripting interface. If FreeCAD has memory leaks, it may crash after running for an extended period or after performing many operations.
  2. Buffer Overflows: A buffer overflow occurs when a program writes data beyond the boundaries of an allocated memory buffer. This can overwrite adjacent memory regions, leading to unpredictable behavior and crashes. Buffer overflows are often caused by programming errors, such as incorrect array indexing or insufficient bounds checking. In FreeCAD, buffer overflows can occur in geometric algorithms, file parsing routines, or other areas where data is processed.
  3. Segmentation Faults: A segmentation fault is a specific type of error that occurs when a program tries to access memory that it does not have permission to access. This can happen if the program tries to read or write to a memory address that is outside of its allocated memory region. Segmentation faults often indicate serious programming errors, such as null pointer dereferences or memory corruption. In FreeCAD, segmentation faults can occur in various parts of the code, especially in low-level routines that interact directly with memory.

In the context of the crash being investigated, the segmentation fault in BOPDS_DS::ShapeInfo(int) const suggests a memory management issue within the Open Cascade Technology (OCC) library. This could be due to a bug in the geometric algorithms or to a problem with how FreeCAD is using the OCC library. To diagnose memory management issues, developers often use specialized tools, such as memory profilers and debuggers. These tools can help identify memory leaks, buffer overflows, and other memory-related errors. Users can also try running FreeCAD with memory debugging options enabled to get more information about memory usage. If memory management issues are suspected, it is important to report them to the FreeCAD developers so that they can be investigated and fixed. In the following sections, we will explore the role of Open Cascade Technology (OCC) and its impact on FreeCAD's stability.

Open Cascade Technology (OCC) and Its Impact

Open Cascade Technology (OCC) is the geometric modeling kernel that forms the foundation of FreeCAD's 3D capabilities. OCC provides a comprehensive set of algorithms and data structures for creating, manipulating, and visualizing 3D geometry. Its robust and versatile nature makes it a popular choice for CAD software, including FreeCAD. However, OCC is a complex piece of software, and bugs within OCC can have a significant impact on FreeCAD's stability and performance. Understanding the role of OCC and its potential issues is crucial for troubleshooting crashes and other problems in FreeCAD.

  1. Geometric Modeling: OCC provides the core geometric modeling algorithms used in FreeCAD, including those for creating primitives, performing Boolean operations, and generating meshes. These algorithms are essential for creating and manipulating 3D shapes in FreeCAD. If there are bugs in the OCC geometric modeling algorithms, it can lead to errors, crashes, or incorrect results.
  2. Boolean Operations: Boolean operations, such as union, difference, and intersection, are fundamental operations in CAD modeling. OCC provides the algorithms for performing Boolean operations on 3D shapes. These algorithms are complex and computationally intensive, and bugs in the Boolean operation algorithms can lead to crashes or incorrect results. The crash being investigated, which occurs during a subtractive cone operation, is likely related to issues in OCC's Boolean operation algorithms.
  3. Data Structures: OCC uses complex data structures to represent 3D shapes, such as B-Rep (Boundary Representation) and CSG (Constructive Solid Geometry). These data structures store information about the faces, edges, vertices, and other geometric elements of the shapes. If there are errors in the data structures or in the algorithms that manipulate them, it can lead to crashes or data corruption.
  4. Numerical Precision: Geometric computations often involve floating-point numbers, which have limited precision. Numerical precision issues can arise when performing complex geometric operations, leading to errors or inconsistencies. OCC has algorithms for handling numerical precision issues, but these algorithms are not foolproof. In certain geometric configurations, numerical precision problems can still lead to crashes or incorrect results.
  5. Performance: OCC's performance can have a significant impact on FreeCAD's overall performance. If OCC's algorithms are slow or inefficient, it can lead to lag or delays in FreeCAD. Optimizing OCC's performance is an ongoing effort in FreeCAD development.

In the context of the crash being investigated, the stack trace points to issues within OCC's BOPAlgo_PaveFiller class, which is responsible for handling the paving and filling algorithms used in Boolean operations. This suggests that the crash may be related to a bug in OCC's Boolean operation algorithms or to a numerical precision issue. To diagnose OCC-related crashes, developers often use specialized debugging tools and techniques. Users can also try simplifying the design or using alternative modeling techniques to avoid triggering the bug. In the following sections, we will explore the significance of BOPAlgo_PaveFiller and its role in Boolean operations.

The Significance of BOPAlgo_PaveFiller

The BOPAlgo_PaveFiller class within the Open Cascade Technology (OCC) library plays a critical role in performing Boolean operations in FreeCAD. Understanding its significance and function is essential for diagnosing crashes related to Boolean operations. This class is responsible for the paving and filling algorithms, which are crucial for ensuring the accuracy and robustness of Boolean operations, especially when dealing with complex shapes.

  1. Paving: Paving refers to the process of dividing the faces of the input shapes into smaller, more manageable patches or tiles. This is done to simplify the computation of intersections and differences between the shapes. The paving algorithm attempts to create a set of patches that cover the faces of the shapes without overlapping or leaving gaps. The quality of the paving can significantly impact the accuracy and performance of the Boolean operation.
  2. Filling: Filling refers to the process of determining which regions of the resulting shape are inside or outside the input shapes. This is done by analyzing the relationships between the patches created during the paving process. The filling algorithm must correctly identify the regions that should be included in the final result and the regions that should be excluded.
  3. Robustness: The paving and filling algorithms must be robust enough to handle a wide range of geometric configurations, including complex shapes, nearly coplanar faces, and tangential edges. These situations can introduce numerical precision issues and make the computation of Boolean operations challenging. The BOPAlgo_PaveFiller class includes various techniques for addressing these challenges and ensuring the robustness of the Boolean operations.
  4. Performance: The performance of the paving and filling algorithms can have a significant impact on the overall performance of Boolean operations. If the algorithms are slow or inefficient, it can lead to long processing times or crashes. The BOPAlgo_PaveFiller class includes optimizations for improving the performance of the paving and filling processes.
  5. Functions: The stack trace from the crash report implicates several functions within BOPAlgo_PaveFiller, such as ForceInterfEF and PutSEInOtherFaces. These functions are responsible for specific aspects of the paving and filling processes, such as handling face intersections and placing special edges in other faces. The fact that the crash occurs within these functions suggests that there may be a bug in the paving or filling algorithms or that the algorithms are encountering a geometric configuration that they cannot handle.

In the context of the crash being investigated, the involvement of BOPAlgo_PaveFiller suggests that the issue may be related to the geometric complexity of the shapes or to a numerical precision problem. It is possible that the paving or filling algorithms are failing to correctly process the shapes, leading to a segmentation fault. To diagnose this type of crash, developers often use specialized debugging tools and techniques. Users can also try simplifying the design or using alternative modeling techniques to avoid triggering the bug. In the following sections, we will investigate the stack trace in more detail and explore potential solutions.

Investigating the Stack Trace

Investigating the stack trace is a crucial step in diagnosing crashes in FreeCAD. The stack trace provides a detailed record of the function calls that led to the crash, allowing developers to pinpoint the exact location of the error. By examining the stack trace, it is possible to identify the functions and classes that are involved in the crash and to understand the sequence of events that led to the failure.

The stack trace provided in the crash report shows that the crash occurs within the BOPDS_DS::ShapeInfo(int) const function in the libTKBO.so.7.8 library, which is part of Open Cascade Technology (OCC). This indicates that the crash is likely related to an issue within OCC's geometric modeling algorithms. The subsequent function calls in the stack trace provide further clues about the nature of the crash:

  1. BOPDS_DS::Shape(int) const: This function likely retrieves information about a geometric shape. The fact that it is called after ShapeInfo suggests that the crash may be related to accessing or processing shape data.
  2. BOPDS_DS::IsValidShrunkData(opencascade::handle<BOPDS_PaveBlock> const&): This function checks the validity of shrunk data, which is likely related to the paving and filling algorithms used in Boolean operations. This suggests that the crash may be related to a problem with the paving or filling process.
  3. BOPAlgo_PaveFiller::ForceInterfEF(NCollection_IndexedMap<opencascade::handle<BOPDS_PaveBlock>, NCollection_DefaultHasher<opencascade::handle<BOPDS_PaveBlock> > > const&, Message_ProgressRange const&, bool): This function is part of the BOPAlgo_PaveFiller class and is responsible for handling face intersections during Boolean operations. The crash may be occurring due to an error in the face intersection algorithm.
  4. BOPAlgo_PaveFiller::PutSEInOtherFaces(Message_ProgressRange const&): This function is also part of the BOPAlgo_PaveFiller class and is responsible for placing special edges in other faces during Boolean operations. The crash may be related to a problem with the edge placement process.
  5. BOPAlgo_PaveFiller::MakeBlocks(Message_ProgressRange const&): This function is responsible for creating blocks during the paving process. The crash may be occurring due to an error in the block creation algorithm.
  6. BOPAlgo_PaveFiller::PerformInternal(Message_ProgressRange const&) and BOPAlgo_PaveFiller::Perform(Message_ProgressRange const&): These functions are the main entry points for the paving and filling algorithms. The fact that the crash occurs within these functions suggests a general problem with the paving or filling process.
  7. BRepAlgoAPI_BuilderAlgo::IntersectShapes(NCollection_List<TopoDS_Shape> const&, Message_ProgressRange const&): This function computes the intersection of shapes. The crash may be occurring due to an error in the shape intersection algorithm.
  8. BRepAlgoAPI_BooleanOperation::Build(Message_ProgressRange const&): This function builds the result of a Boolean operation. The crash may be occurring during the Boolean operation building process.
  9. FCBRepAlgoAPI_BooleanOperation::Build(Message_ProgressRange const&): This is a FreeCAD-specific function that wraps the OCC Boolean operation building process. The crash may be related to FreeCAD's handling of Boolean operations.
  10. Part::TopoShape::makeElementBoolean(char const*, std::vector<Part::TopoShape, std::allocator<Part::TopoShape> > const&, char const*, double): This function is responsible for creating a Boolean operation element in the Part workbench. The crash may be related to the interaction between the Part workbench and the Boolean operation algorithms.
  11. PartDesign::FeaturePrimitive::execute(TopoDS_Shape const&) and PartDesign::Cone::execute(): These functions are responsible for executing the cone feature primitive in the Part Design workbench. The crash may be specific to the cone feature or to the interaction between the cone feature and the Boolean operation.

By examining the stack trace, it is clear that the crash is related to a complex interaction between the geometric modeling algorithms in OCC, the paving and filling processes in BOPAlgo_PaveFiller, and the Boolean operation building process. The fact that the crash occurs within the cone feature in the Part Design workbench suggests that the issue may be specific to the interaction between the cone and the Boolean operation. To further investigate the crash, it is necessary to examine the FreeCAD file and the specific geometric data involved in the operation. In the following sections, we will explore the FreeCAD file and attempt to reproduce the error.

Examining the FreeCAD File

Examining the FreeCAD file (crash.FCStd) is a critical step in understanding the context of the crash. The file contains the entire design, including the geometric data, sketches, and operations performed. By opening the file and inspecting its contents, it is possible to gain valuable insights into the potential causes of the crash.

  1. Model History: The FreeCAD file stores the model history, which is a record of all the operations performed on the design. By examining the model history, it is possible to understand the sequence of steps that led to the crash. This can help identify the specific operation or combination of operations that triggered the issue.
  2. Sketches: Sketches are used to define the 2D profiles that are used to create 3D shapes. The FreeCAD file contains the sketches used in the design, including the circle sketch that was selected before the crash. By examining the sketch, it is possible to identify potential issues, such as self-intersections, overlapping elements, or invalid constraints.
  3. Geometric Data: The FreeCAD file contains the geometric data for all the shapes in the design. This data includes information about the faces, edges, vertices, and other geometric elements of the shapes. By examining the geometric data, it is possible to identify potential issues, such as geometric complexities, numerical precision problems, or invalid shapes.
  4. Feature Parameters: Features in FreeCAD, such as cones, cylinders, and Boolean operations, have parameters that control their behavior. The FreeCAD file contains the values of these parameters. By examining the feature parameters, it is possible to identify potential issues, such as incorrect dimensions or invalid settings.
  5. Add-on Usage: The FreeCAD file indicates which add-ons were used in the design. In this case, the ThreadProfile add-on was used. This is an important clue, as the add-on may be contributing to the crash. By understanding how the add-on was used, it is possible to identify potential issues related to the add-on.

To examine the FreeCAD file, it is necessary to open it in FreeCAD and inspect its contents. This can be done by double-clicking the file or by using the "File -> Open" menu in FreeCAD. Once the file is open, it is possible to navigate the model history, examine the sketches, inspect the geometric data, and view the feature parameters. By carefully examining the FreeCAD file, it is possible to gain a deeper understanding of the crash and to identify potential solutions. In the following sections, we will attempt to reproduce the error and explore potential workarounds.

Reproducing the Error

Reproducing the error is a crucial step in verifying the bug and developing a fix. By following the steps that led to the crash, it is possible to confirm that the bug exists and to gather more information about its behavior. Reproducing the error also allows developers to test potential fixes and ensure that they resolve the issue without introducing new problems.

To reproduce the error in this case, the following steps should be followed:

  1. Open the FreeCAD file (crash.FCStd) in FreeCAD.
  2. Select the circle sketch in the model tree.
  3. Switch to the Part Design workbench.
  4. **Click the