apache/cassandra · error · UnsupportedOperationException

Token type does not support token allocation.

Error message

Token type %s does not support token allocation.

What it means

ComparableObjectToken overrides size(Token) to always throw UnsupportedOperationException: object-backed tokens (e.g. LocalPartitioner tokens) have no meaningful numeric ring size for the token-allocation algorithms. This is the default 'allocation not supported' stub inherited by such token implementations.

Solutions

1. Do not use token allocation with this partitioner; assign tokens explicitly.
2. Restructure code to only invoke allocation for numeric-token partitioners (check token type before calling size()).
3. Override size() in a custom Token subclass if you implement your own allocation-aware token type.

Example fix

// before
double size = token.size(next);  // throws for object tokens
// after
double size = token instanceof ComparableObjectToken ? 0.0 /* non-allocatable */ : token.size(next);

if (token instanceof ComparableObjectToken)
    throw new IllegalStateException("Token allocation unsupported for object tokens");

boolean isAllocatable(Token t) { return t instanceof Murmur3Partitioner.LongToken; }

try {
    double s = token.size(next);
} catch (UnsupportedOperationException e) {
    // object tokens are not allocation-aware
}

When it happens

Trigger: Calling size() on any ComparableObjectToken instance (e.g. LocalPartitioner tokens), directly or via TokenAllocation.allocateTokens / replication-factor-based token allocation during bootstrap.

Common situations: Using allocate_tokens_for_local_replication_factor or custom allocation code with LocalPartitioner (keyspaces backed by local data) or another object-token partitioner; tools assuming numeric tokens.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

• Token type does not support token allocation.
• Aggregate function cannot be used for masking table columns
• Allocated token already assigned to node . Is another node…
• Altering field types is no longer supported
• Cannot assassinate the node when sequence of kind

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/7ef721b05f567409. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/dht/ComparableObjectToken.java:73

    public int hashCode()
    {
        return token.hashCode();
    }

    @Override
    @SuppressWarnings("unchecked")
    public int compareTo(Token o)
    {
        if (o.getClass() != getClass())
            throw new IllegalArgumentException(String.format("Invalid type of Token.compareTo() argument. %s != %s", o.getClass(), getClass()));

        return token.compareTo(((ComparableObjectToken<C>) o).token);
    }

    @Override
    public double size(Token next)
    {
        throw new UnsupportedOperationException(String.format("Token type %s does not support token allocation.",
                                                              getClass().getSimpleName()));
    }

    @Override
    public Token nextValidToken()
    {
        throw new UnsupportedOperationException(String.format("Token type %s does not support token allocation.",
                                                              getClass().getSimpleName()));
    }

    @Override
    public Token decreaseSlightly()
    {
        throw new UnsupportedOperationException(String.format("Token type %s does not support token allocation.",
                                                              getClass().getSimpleName()));
    }
}

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