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Angular’s NG3003 means the compiler would need to add an import for a component, directive, or pipe used in a template, but that import would create a cycle. Start with the file path shown in the error, trace the dependency back to the component being compiled, then remove the back-reference or—where appropriate—use an NgModule compilation path that supports remote scoping. Angular’s NG3003 reference documents the diagnostic and its remedies.
What NG3003 means
NG3003, “Import Cycle Detected,” is a compiler diagnostic about a template dependency. A component’s template references a component, directive, or pipe, and compiling that reference would require Angular to add an import. If the referenced declaration already depends on the component being compiled, the added import would close a cycle.
For example, a parent component’s template uses a child component, while the child imports or injects the parent. The compiler-generated dependency can form parent.ts -> child.ts -> parent.ts. The issue is not simply that Angular found any circular dependency: NG3003 identifies a cycle that would be introduced by an import needed to compile a template reference.
How to trace the cycle in the error
- Read the emitted path. Angular includes the generated cycle in the diagnostic, such as
/parent.ts -> /child.ts -> /parent.ts. Treat that path as the starting point rather than guessing from the error name. - Identify the component being compiled. Check which component, directive, or pipe is named by the diagnostic, then note the template reference that requires Angular to import another declaration.
- Follow the dependency back. Inspect the files in the path to find the import or other dependency that points back to the original declaration. In the parent-child example, the parent template needs the child, and the child has a dependency on the parent.
- Choose a fix that removes the cycle-causing file dependency. Restructure the shared contract, colocate mutually dependent classes, or use a type-only import if the imported declaration is needed only as a type.
Choose a fix that matches the dependency
| Approach | When it fits | What it changes | Important boundary |
|---|---|---|---|
| Move a shared abstraction to an independent file | Both sides need the same interface or contract, but should not depend on each other directly. | Both declarations import the shared interface from a separate file, removing the direct back-reference. | The interface should represent the shared contract; moving it does not itself remove a separate runtime dependency if one remains. |
| Colocate mutually dependent classes | Two classes genuinely reference one another and can reasonably live in one file. | Removes the import edge between those files, so that edge cannot participate in the cycle. | Use this when the shared-file arrangement remains understandable and maintainable. |
Use import type |
The imported declaration is used only in a type position. | Makes the import type-only; Angular notes that type-only imports do not contribute to the cycle. | Do not use it when the declaration is needed as a runtime value, such as for runtime behavior or a value reference. |
| Rely on NgModule remote scoping | An NgModule-based application can connect the dependencies through its NgModule rather than adding the cycle-causing import to the component. | Angular places additional remote-scoping code in the NgModule. | The code is side-effectful and prevents tree shaking. Angular says this approach cannot be used in libraries; a library using compilationMode: partial raises NG3003 when a component needs a cyclic import. |
Why library builds can expose NG3003
NgModule remote scoping is a workaround for some application builds, not a general solution for libraries. Because the generated remote-scoping code is side-effectful and prevents tree shaking, Angular cannot use it in libraries. In partial-compilation mode, a library component that needs a cycle-causing import therefore surfaces NG3003. For that case, fix the dependency structure—such as by extracting a shared interface, colocating mutually dependent classes, or making a genuinely type-only import—instead of relying on remote scoping.
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Keep the diagnosis focused
Use the compiler’s cycle path to distinguish NG3003 from other circular-dependency problems in an Angular project. This diagnostic concerns an import the compiler would need for a referenced component, directive, or pipe; tracing that specific path reveals the dependency direction that must change.
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