FasterXML/jackson-databind · error · IllegalArgumentException

Cannot use FormatSchema of type {} for format {}

Error message

Cannot use FormatSchema of type {} for format {}

What it means

ObjectReader._verifySchemaType() checks that a FormatSchema (e.g. a CSV schema, Avro schema, YAML schema) is usable by the underlying parser factory before deserialization begins. If the schema's type doesn't match the dataformat the reader is configured for (e.g. a CsvSchema on a JSON JsonMapper's reader), Jackson throws IllegalArgumentException naming both the schema class and the expected format. This prevents a silent wrong-format parse that would produce garbage.

Source

Thrown at src/main/java/tools/jackson/databind/ObjectReader.java:2093

                if (_valueToUpdate != null) {
                    bt = _valueToUpdate.getClass();
                }
            }
            ctxt.reportTrailingTokens(bt, p, t);
        }
    }

    /*
    /**********************************************************************
    /* Internal methods, other
    /**********************************************************************
     */

    protected void _verifySchemaType(FormatSchema schema)
    {
        if (schema != null) {
            if (!_parserFactory.canUseSchema(schema)) {
                    throw new IllegalArgumentException("Cannot use FormatSchema of type "+schema.getClass().getName()
                            +" for format "+_parserFactory.getFormatName());
            }
        }
    }

    /**
     * Internal helper method called to create an instance of {@link DeserializationContext}
     * for deserializing a single root value.
     * Can be overridden if a custom context is needed.
     */
    protected DeserializationContextExt _deserializationContext() {
        return _contexts.createContext(_config, _schema, _injectableValues);
    }

    protected DeserializationContextExt _deserializationContext(JsonParser p) {
        return _contexts.createContext(_config, _schema, _injectableValues)
                .assignParser(p);
    }

View on GitHub (pinned to a50c7d2a1d)

Solutions

1. Use the format-specific mapper that owns the schema: CsvMapper for CsvSchema, YAMLMapper for YAMLFactory's schema, etc.
2. Obtain the schema from the same module/factory as the reader: mapper.schemaFor(...) or mapperFactory.getFormatSchema(...).
3. Verify schema compatibility before assigning: if (!mapper.tokenStreamFactory().canUseSchema(schema)) fail fast with your own message.
4. Check that you built the reader from the same JsonMapper/Factory instance that produced the schema, especially in DI containers.

Example fix

// before
JsonMapper jsonMapper = JsonMapper.builder().build();
CsvSchema csv = CsvSchema.builder().build();
ObjectReader r = jsonMapper.reader(csv); // throws: CSV schema on JSON reader
// after
CsvMapper csvMapper = CsvMapper.builder().build();
CsvSchema csv = csvMapper.schemaFor(MyType.class);
ObjectReader r = csvMapper.reader(csv);

// Verify schema compatibility before assigning it to a reader
if (schema != null && !mapper.tokenStreamFactory().canUseSchema(schema)) {
    throw new IllegalArgumentException("schema " + schema.getClass() + " not for " + mapper.tokenStreamFactory().getFormatName());
}
ObjectReader r = mapper.reader(schema);

boolean schemaMatches(JsonMapper m, FormatSchema s) {
    return s != null && m.tokenStreamFactory().canUseSchema(s);
}

try {
    return mapper.reader(schema).readValue(input);
} catch (IllegalArgumentException e) {
    if (e.getMessage().startsWith("Cannot use FormatSchema")) {
        // resolve to the correct format-specific mapper and retry
    }
    throw e;
}

When it happens

Trigger: Calling reader.forSchema(csvSchema) on a reader obtained from a JsonMapper; mixing schema objects across dataformat modules (AvroSchema on a YAML reader, etc.); passing a schema loaded generically as FormatSchema without checking the originating module; using a base ObjectMapper instead of the format-specific mapper (CsvMapper, YAMLMapper) when a schema is required.

Common situations: Copy-paste wiring where a schema built for one dataformat is reused against a different mapper; autowiring the wrong ObjectMapper bean in a Spring setup with multiple format mappers; upgrading a dataformat module that changed its FormatSchema class so the old instance no longer matches; CSV/Avro/Parquet/Protobuf schemas all being 'FormatSchema' but mutually incompatible.

Related errors

• Cannot use FormatSchema of type {} for format {}
• maxProblems must be positive
• AnnotationIntrospector returned Converter definition of type
• AnnotationIntrospector returned Class {}; expected Class<Con
• Invalid abstract type resolution from {} to {}: latter is no

AI-assisted analysis of FasterXML/jackson-databind@a50c7d2a1d (2026-08-06). Data as JSON: /api/errors/4bcbbf227cf24087. Report an issue: GitHub.