apache/cassandra · error · ConfigurationException

It was not possible to generate a valid password in

Error message

It was not possible to generate a valid password in %s attempts. Check your configuration and try again.

What it means

The password generator tries up to maxPasswordGenerationAttempts times to randomly produce a password that passes the configured validator (including dictionary checks). If no generated password passes within that budget, it throws a ConfigurationException, indicating the validator constraints are too strict or contradictory relative to the generation strategy.

Solutions

1. Relax the validator constraints (lower minimum lengths, broaden character set requirements) so random generation can succeed
2. Increase maxPasswordGenerationAttempts in the password generator configuration
3. Check the dictionary rule: if the dictionary rejects most strings, narrow the rule or regenerate passwords with more entropy
4. Generate the password manually and verify it with the validator's validation logic before setting it

Example fix

// before
maxPasswordGenerationAttempts = 100, min_length = 40 with strict characteristic rules
// after
Increase attempts: set password_generation.attempts to 1000, or reduce min_length to 16

// Validate that a manually chosen sample password passes before relying on generation
boolean sampleOk = validator.validate(samplePassword).isValid();
if (!sampleOk) throw new IllegalStateException("Validator rejects even hand-crafted passwords; config too strict");

try {
    String pw = generator.generate();
} catch (ConfigurationException e) {
    if (e.getMessage().contains("generate a valid password")) {
        // relax validator constraints or raise maxPasswordGenerationAttempts, then retry
    }
}

When it happens

Trigger: Validator configured with requirements the generator's random construction rarely or never satisfies (e.g. very long minimum length combined with special-character or dictionary rules); a dictionary rule that rejects nearly all candidate passwords; an excessively low maxPasswordGenerationAttempts.

Common situations: Operators add a large dictionary file that rejects most candidates; strict length/characteristic minimums combined with default attempt limits; tests exercising testPasswordGenerationLength or password generation with a misconfigured validator.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• must be positive.
• The shortest password to pass the failing validator for any
• default_keyspace_rf to be set
• default_keyspace_rf to be set
• Dictionary file does not exist.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/840d2c7eb70707ae. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/db/guardrails/CassandraPasswordGenerator.java:74

        passwordGenerator = new PasswordGenerator();
    }

    @Override
    public String generate(ValueValidator<String> validator, Map<String, Object> options)
    {
        boolean dictionaryAware = validator instanceof PasswordDictionaryAware;

        for (int i = 0; i < maxPasswordGenerationAttempts; i++)
        {
            String generatedPassword = passwordGenerator.generatePassword(configuration.lengthWarn, characterRules);
            if (validator.shouldWarn(generatedPassword, false).isEmpty())
            {
                if (!dictionaryAware || ((PasswordDictionaryAware<?>) validator).foundInDictionary(generatedPassword).isValid())
                    return generatedPassword;
            }
        }

        throw new ConfigurationException("It was not possible to generate a valid password " +
                                         "in " + maxPasswordGenerationAttempts + " attempts. " +
                                         "Check your configuration and try again.");
    }

    @Nonnull
    @Override
    public CustomGuardrailConfig getParameters()
    {
        return configuration.asCustomGuardrailConfig();
    }

    @Override
    public void validateParameters() throws ConfigurationException
    {
        configuration.validateParameters();
    }

    protected List<CharacterRule> getCharacterGenerationRules(int upper, int lower, int digits, int special)

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