What's New For the January 2026 Release

Enhancements

Changes to Support Design Intent

This release introduces a new design-intent experience with three design types: hybrid, part, and assembly. Hybrid is the design type that Fusion has always supported. The part and assembly design types are new. If you use the hybrid design type, there is no change. However, for part or assembly designs, there are significant changes to the user interface and how Fusion behaves. This also affects add-in commands, and most will need to be updated to handle it correctly.

Depending on what your add-in does, it’s possible that it may not function correctly when run in a part design. It should behave the same as it does today for hybrid designs. For assembly designs, your command will not be available by default. You must explicitly enable it to be displayed for assemblies, and in most cases you will also need to modify the command logic to be compatible with assembly designs. For more information, see the new Programming for Design Intent topic in the API User Manual.

Some new functionality has been added to the API to support this, including Design.designIntent, Design.isModelingInAssemblyEnabled, and Occurrences.addNewExternalComponent. The Spur Gear sample program has been updated to fully support the new design types. Some other samples have been modified to verify that the required design type is active and will exit with a warning if it is not.

In most cases, the API has the same capabilities and limitations as the user interface. However, there is currently one exception: the API allows the creation of new internal components, which is not possible through the user interface. It is unclear whether this capability will remain in the future, so it is recommended that add-ins do not rely on this behavior.

As a user, if you need access to the functionality provided by an add-in that has not yet been updated, you can revert to using a hybrid design.
Python Update
This Fusion release updates the Python version from 3.12 to 3.14. Besides the API, Fusion uses Python for a few other things, and this Python update includes some security fixes. Most people won't notice any change. Those affected are the developers and users of any Python apps delivered as .pyc files. Previous versions of these add-ins will fail to load because .pyc files are tied to the minor version of Python that was used to create them. This change does not affect any add-ins where the .py source code is available. This change only applies to the embedded Python runtime shipped with Fusion and is independent of any system-installed Python.

If you deliver apps as pyc files, you need to test your add-in and rebuild it to get new pyc files that you can make available to your users.

If you're a user and are seeing the message shown below when you start Fusion, you have an impacted add-in and need a new version. Check the Autodesk App Store or the developer's website to download a new compatible version, install it, and continue using it as before. If you can't find an updated app, contact the app developer directly.
API Support for Derive
The API now supports deriving components. This includes the ability to create, query, and edit a Derive feature, as well as to query entities that support being derived to determine whether they were derived and, if so, which derive feature created them.

All entity types that support being derived now provide an isDerived property, which indicates whether the entity was derived into the current design. If this is true, the entity behaves as read-only. These entities also support a new deriveFeature property, which returns the Derive feature that created the entity when isDerived is true.
Sketch Auto Constrain
The API now supports the auto constraint functionality in sketch. This functionality is exposed as a preview API, so please use it and provide feedback on what you liked or didn't like.
User Interface Themes
With the introduction of the dark user interface theme in Fusion, only two themes are now supported: light gray and dark blue. The User Manual topic on the user interface has been updated to discuss the icons used for different themes.
API For the New Assembly Constraint Functionality is Still in Progress
The July release began introducing some of the API for the new assembly constraint functionality. It is a preview feature, and since July, the functionality in Fusion has been modified, necessitating an API change. The changes are still ongoing, so nothing has changed since then. However, we will be introducing a new Constraints API in the future, so if you start using this API, be aware that your existing code will need to be updated to function correctly.

Fixes

corbin2 reported a problem on the forum about a failure when using ThroughAllExtent to extrude sketch text. This has been fixed.

Custom Features

Custom Features is a new functionality that is currently in preview. This release has nothing new for custom features, but we still encourage you to try it and let us know your thoughts. You can learn more about it in the Custom Feature topic in the API User Manual. There are also two add-in samples referenced in that document that you can use to see the functionality.

This functionality is provided as a preview of intended future API capabilities. You are encouraged to use it and report any problems or suggestions using the Fusion API and Scripts Forum. However, because this previews future functionality, it may change, breaking any existing programs that use it. Therefore, you should never deliver programs that utilize any preview capabilities.

New Objects

Name	Description
AutoConstrainInput	The AutoConstrainInput object is used to define the various options when adding dimension and geometric constraints to help constrain a sketch.
AutoConstrainResult	Provides the result information after a sketch auto constrain operation has been executed. This object contains details about what constraints and dimensions were added and whether the sketch was successfully fully constrained.
CornerClosureFeature	Defines a corner closure feature, providing methods to redefine the type of corner closure.
CornerClosureFeatureDefinition	A Base class to return the information used to define the CornerClosureFeature.
CornerClosureFeatureInput	This class defines the methods and properties that pertain to the definition of a corner closure feature.
CornerClosureFeatures	Collection that provides access to all of the existing corner closure features in a design and supports the ability to create new corner closure features.
CornerClosureInputDefinition	Defines the common input properties shared by both two-bend and three-bend corner closure features. This class provides the fundamental properties required for any corner closure operation, including miter gap, alignment settings, and bend transition behavior.
DerivedParameter	Represents a parameter that is derived from another design.
DeriveFeature	Object that represents an existing derive feature in a design.
DeriveFeatureInput	This class defines the methods and properties that pertain to the definition of a derive feature.
DeriveFeatures	Collection that provides access to all of the existing derive features in a component and supports the ability to create new derive features.
ExtruderMachineElement	Machine element representing an extruder on a fused filament fabrication (FFF) machine. A machine can have multiple extruders and thus multiple ExtruderMachineElement elements.
ExtruderMachineElementInput	Specialization of MachineElementInput for creating an additive FFF extruder element.
ThreeBendCornerClosureFeatureDefinition	The definition for a three bend corner closure.
ThreeBendCornerClosureInputDefinition	Defines the input properties required for creating a three-bend corner closure feature. This input definition provides a structured way to organize and validate the parameters before passing them to the setThreeBendCornerClosure method.
TwoBendCornerClosureFeatureDefinition	The definition for a two bend corner closure.
TwoBendCornerClosureInputDefinition	Defines the input properties required for creating a two-bend corner closure feature. This input definition provides a structured way to organize and validate the parameters before passing them to the setTwoBendCornerClosure method.

New Methods, Properties and Events

Name	Description
BRepBody.deriveFeature	Returns the DeriveFeature if this BRepBody is derived from another design. This property returns null if the BRepBody is not derived from another design (i.e. isDerived property returns false).
BRepBody.isDerived	Returns if this BRepBody is derived from another design. If true, this body cannot be deleted.
CAM3MFExportOptions.isSliceDataIncluded	Flag toggling if slice data which has been generated beforehand by generating the entire setup or the additive toolpath object should be included in the exported file. The default value is false.
CAMTemplate.attributes	Returns the collection of attributes associated with this template.
Canvas.deriveFeature	Returns the DeriveFeature if this canvas is derived from another design. This property returns null if the canvas is not derived from another design (i.e. isDerived property returns false).
Canvas.isDerived	Returns if this canvas is derived from another design. If true, the canvas cannot be deleted. You should not attempt to make any edits to the derived canvas. Any edits made to this derived canvas will be lost when the derive updates.
ConfigurationParameterCell.textValue	Gets and sets the text value of the parameter when it is a text parameter. This can be determined by checking the valueType property. Setting this value will cause the current expression to be overwritten. This property behaves as read-only when the table is obtained from a DataFile object.
ConfigurationParameterCell.valueType	Returns the type of value this parameter cell is. For a numeric parameter, you can get the value using the value property. For a text parameter, you can get the value using the textValue property.
ConstructionAxis.deriveFeature	Returns the DeriveFeature if this construction axis is derived from another design. This property returns null if the construction axis is not derived from another design (i.e. isDerived property returns false).
ConstructionAxis.isDerived	Returns if this construction axis is derived from another design. If true, the construction axis cannot be deleted. You should not attempt to make any edits to the derived construction axis. Any edits made to this derived construction axis will be lost when the derive updates.
ConstructionPlane.deriveFeature	Returns the DeriveFeature if this construction plane is derived from another design. This property returns null if the construction plane is not derived from another design (i.e. isDerived property returns false).
ConstructionPlane.isDerived	Returns if this construction plane is derived from another design. If true, the construction plane cannot be deleted. You should not attempt to make any edits to the derived construction plane. Any edits made to this derived construction plane will be lost when the derive updates.
ConstructionPoint.deriveFeature	Returns the DeriveFeature if this construction point is derived from another design. This property returns null if the construction point is not derived from another design (i.e. isDerived property returns false).
ConstructionPoint.isDerived	Returns if this construction point is derived from another design. If true, the construction point cannot be deleted. You should not attempt to make any edits to the derived construction point. Any edits made to this derived construction point will be lost when the derive updates.
Decal.deriveFeature	Returns the DeriveFeature if this decal is derived from another design. This property returns null if the decal is not derived from another design (i.e. isDerived property returns false).
Decal.isDerived	Returns if this decal is derived from another design. If true, the canvas cannot be deleted. You should not attempt to make any edits to the derived decal. Any edits made to this derived decal will be lost when the derive updates.
Design.derivedParameters	Returns a read only list of all parameters that are derived into the design. This includes the user parameters and model parameters from all derives in this design.
Design.designIntent	Gets and sets the use intent of this design. Changing the design intent from one type to another is not supported in all cases. For example, if an assembly contains any external or internal components it cannot be converted to a part.
Design.isModelingInAssemblyEnabled	If this design is an assembly, this property gets and sets if the modeling functionality is enabled. If this design is a part or hybrid design, the value of this property should be ignored.
Features.cornerClosureFeatures	Returns the collection that provides access to the existing Corner Closure features.
Features.deriveFeatures	Returns the collection that provides access to the Derive features within the component and supports the creation of new Derive features.
FlatPatternProduct.derivedParameters	Returns a read only list of all parameters that are derived into the design. This includes the user parameters and model parameters from all derives in this design.
FlatPatternProduct.designIntent	Gets and sets the use intent of this design. Changing the design intent from one type to another is not supported in all cases. For example, if an assembly contains any external or internal components it cannot be converted to a part.
FlatPatternProduct.isModelingInAssemblyEnabled	If this design is an assembly, this property gets and sets if the modeling functionality is enabled. If this design is a part or hybrid design, the value of this property should be ignored.
FusionProductPreferences.isAutoLookAtSketch2	Gets and sets if the view is re-oriented to view the newly created sketch, and if it is re-oriented, if the camera uses the current camera settings or is orthographic.
GeneralPreferences.activeUserInterfaceTheme	Gets the active user interface theme. This property is only different from userInterfaceTheme in the case the theme is DeviceUserInterfaceTheme. In that case the theme used will be returned.
Occurrence.deriveFeature	Returns the DeriveFeature if this occurrence is derived from another design. This property returns null if the occurrence is not derived from another design (i.e. isDerived property returns false).
Occurrence.isDerived	Returns if this occurrence is derived from another design. If true, the occurrence cannot be deleted. You should not attempt to make any edits to the component referenced by the derived occurrence. Any edits made to this derived occurrence will be lost when the derive updates.
Occurrences.addNewExternalComponent	Method that creates a new occurrence by creating a new external component (X-Ref) that is not saved yet. This is similar to the "New Component" command in the UI when creating an external component, where you specify a name and location but the component is created in-memory without being saved immediately. This allows programs to create and populate an external component without needing to save it first, and makes undo possible. The component will be saved automatically when the parent assembly is saved.
PrintSetting.toXML	Generates and returns the print setting xml content string.
RecognizedHole.getHoleSignatureXML	Convert hole signature to XML. The result can be used to create a hole template.
Sketch.autoConstrain	Auto constrains the sketch using the information provided by the input object. This returns a single locally computed solution.
Sketch.createAutoConstrainInput	Creates a new AutoConstrainInput object associated with this sketch. The input object is used to define the various options when adding dimension and geometric constraints to help constrain a sketch. The returned object has all options defined with default values and additional constraints can be applied by passing this into the autoConstrain method.
Sketch.deriveFeature	Returns the DeriveFeature if this sketch is derived from another design. This property returns null if the sketch is not derived from another design (i.e. isDerived property returns false).
Sketch.isDerived	Returns if this sketch is derived from another design. If true, the sketch cannot be deleted. You should not attempt to make any edits to the derived sketch. Any edits made to this derived sketch will be lost when the derive updates.
SketchLines.addByMidpoint	Creates a sketch line where the first point is the midpoint and the second point is one endpoint. The system automatically calculates the other endpoint to create a line where the first point is exactly at the midpoint.
Tool.description	Gets the descriptive text about the tool. Includes various pieces of information depending on the tool type. Usually contains the tool number, data describing the tool geometry and the description. In the UI, the same information is displayed in the operation tree or in the tool library table.
WorkingModel.derivedParameters	Returns a read only list of all parameters that are derived into the design. This includes the user parameters and model parameters from all derives in this design.
WorkingModel.designIntent	Gets and sets the use intent of this design. Changing the design intent from one type to another is not supported in all cases. For example, if an assembly contains any external or internal components it cannot be converted to a part.
WorkingModel.isModelingInAssemblyEnabled	If this design is an assembly, this property gets and sets if the modeling functionality is enabled. If this design is a part or hybrid design, the value of this property should be ignored.

Help created: Tuesday, January 20, 2026 8:01 AM