apache/cassandra · error · InvalidRequestException

A user type cannot contain counters

Error message

A user type cannot contain counters

What it means

Validation guard in CreateTypeStatement.apply() fired while creating a user-defined type: one of the declared field types is a counter type. Cassandra UDTs are stored as static schema metadata with no write path for counter increments, so a counter field inside a UDT is illegal; the create is rejected with InvalidRequestException before the schema change is applied.

Solutions

1. Remove the counter-typed field from the CREATE TYPE declaration and create the type again without it; if counters are required, keep them in a regular counter table instead of a UDT; nest or reference counter data by primary key rather than embedding it in the UDT.

When it happens

Trigger: Thrown at src/java/org/apache/cassandra/cql3/statements/schema/CreateTypeStatement.java:112 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/b17585297bcbe62a. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/cql3/statements/schema/CreateTypeStatement.java:112

        UserType existingType = keyspace.types.getNullable(bytes(typeName));
        if (null != existingType)
        {
            if (ifNotExists)
                return schema;

            throw ire("A user type with name '%s' already exists", typeName);
        }

        Set<FieldIdentifier> usedNames = new HashSet<>();
        for (FieldIdentifier name : fieldNames)
            if (!usedNames.add(name))
                throw ire("Duplicate field name '%s' in type '%s'", name, typeName);

        for (CQL3Type.Raw type : rawFieldTypes)
        {
            if (type.isCounter())
                throw ire("A user type cannot contain counters");

            if (type.isUDT() && !type.isFrozen())
                throw ire("A user type cannot contain non-frozen UDTs");
        }

        List<AbstractType<?>> fieldTypes =
            rawFieldTypes.stream()
                         .map(t -> t.prepare(keyspaceName, keyspace.types).getType())
                         .collect(toList());

        UserType udt = new UserType(keyspaceName, bytes(typeName), fieldNames, fieldTypes, true);
        return schema.withAddedOrUpdated(keyspace.withSwapped(keyspace.types.with(udt)));
    }

    SchemaChange schemaChangeEvent(KeyspacesDiff diff)
    {
        return new SchemaChange(Change.CREATED, Target.TYPE, keyspaceName, typeName);
    }

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