Jackson’s “no Creators” deserialization exception means it could not find a usable way to construct the requested Java type from the JSON input. For an immutable class, the clearest fix is usually an explicit property-based creator: annotate the constructor with @JsonCreator and each parameter with @JsonProperty. But first check the complete exception: a creator that exists but does not match the incoming JSON shape is a different problem from having no applicable creator at all.
What the exception means
Jackson has to create an instance before it can populate or return the deserialized object. A class with only a parameterized constructor can fail when Jackson cannot identify that constructor as a creator or map its parameters to the JSON properties. JSON keys matching Java field names do not, by themselves, establish how constructor arguments should be mapped.
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A common example is: Cannot construct instance of ... (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator). The class name and final wording vary by case; do not diagnose from the opening phrase alone.
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- Read the full exception and reference chain. Identify the exact target type Jackson was trying to create, and whether the input at that point is an object, scalar, array, or another token shape.
- Inspect the target type. Check whether it is concrete, which constructors and static factory methods it has, whether they are visible, and whether any are annotated as creators. An abstract target may need a concrete subtype or type information rather than another constructor.
- Compare the available creators with the input. Jackson’s
DeserializationContextdistinguishes a missing-instantiator case from an input mismatch: if no applicable creator exists, it reports a bad type definition; if creators exist but none matches the input token, it reports an input mismatch. As the Jackson source comment puts it, “This is either a definition problem (if no applicable creator exists), or input mismatch problem (otherwise) since none of existing creators match with token.” - Check the application’s Jackson and Java setup. Record the Jackson versions, Java version, compiler parameter settings, registered modules, and any
ObjectMapperconstructor-detection configuration. These can affect parameter-name discovery and creator selection.
Choose a construction approach that fits the model
| Situation | Approach | What to check |
|---|---|---|
| Mutable class with writable properties | Provide a no-argument constructor and writable properties. | The constructor and setters or other writable properties must be accessible to Jackson. This approach allows construction first and property assignment afterward. |
| Immutable class with named JSON fields | Use a property-based constructor annotated with @JsonCreator and annotate each argument with its corresponding @JsonProperty. |
Each annotation name must match the intended JSON contract. This makes the argument-to-property mapping explicit. |
| Constructor parameter names retained by compilation | For the Jackson 2.x setup described by Baeldung, use ParameterNamesModule and compile with -parameters. |
Both compiler metadata and module configuration matter. Verify behavior against the exact Jackson dependencies in the application. |
| Constructor selection requires configuration | Consider ConstructorDetector, documented as available since Jackson 2.12. |
Its selection policy must fit the class’s constructors and annotations. Check the API for the project’s Jackson release rather than copying configuration from another version. |
| Java record | Jackson uses the canonical constructor in the documented cases. | A no-argument constructor is not inherently required. Custom constructors, factories, aliases, nested types, input shape, and Jackson version can change what needs inspection. |
| Static factory is the intended construction path | Identify the factory explicitly as a creator and map its inputs. | The mere presence of a factory method does not guarantee Jackson will select it. |
Explicit creator for an immutable class
For a class whose JSON object contains message and priority, the constructor mapping should be explicit:
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public class Notification {
private final String message;
private final int priority;
@JsonCreator
public Notification(
@JsonProperty("message") String message,
@JsonProperty("priority") int priority) {
this.message = message;
this.priority = priority;
}
}This tells Jackson which constructor to use and which input property supplies each argument. It is a suitable pattern when the class is intended to remain immutable; adding a mutable no-argument path solely to silence the exception may not fit that design.
Version-sensitive behavior to verify
Baeldung’s focused example reproduces the exception with Jackson 2.17.2 and describes parameter-name discovery with ParameterNamesModule and compilation using -parameters for Jackson 2.x. It reports that this functionality is built into Jackson Databind and enabled by default in Jackson 3.x. Because this behavior depends on the actual release and configuration, confirm it against the dependencies used by the application before changing compiler or mapper settings.
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A separate Baeldung tutorial describes ConstructorDetector support from Jackson 2.12 and record deserialization through the canonical constructor. Its illustrated non-canonical record constructor is not used even when annotated. Treat that as release- and class-shape-sensitive guidance, especially when records have custom constructors or factories.
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Change one relevant part of the construction path, then retry deserialization using the actual payload that triggered the error. If the exception changes, inspect the new full message and reference chain: resolving instance creation does not guarantee that every property or nested value can be mapped. If the issue remains ambiguous, the useful diagnostic details are the complete stack trace, target class, constructor and factory signatures, representative JSON, Java and Jackson versions, compiler parameter settings, and ObjectMapper modules or detector configuration.
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