testcontainers/testcontainers-java · error · IllegalArgumentException

Null password is not allowed

Error message

Null password is not allowed

What it means

MSSQLServerContainer.withPassword() validates the supplied sa password via checkPasswordStrength(). If the argument is null, it throws this IllegalArgumentException immediately rather than deferring failure to container startup. SQL Server images reject empty/null credentials, so the library fails fast.

Solutions

  1. Pass a non-null password string, e.g. withPassword("yourStrong(!)Password")
  2. Check the config source that produced null and set the password before calling withPassword()
  3. Use a container default like MSSQLServerContainer.DEFAULT_PASSWORD if you did not intend to override it

Example fix

// before
container.withPassword(System.getenv("SA_PASSWORD")); // may be null
// after
String pw = System.getenv("SA_PASSWORD");
Objects.requireNonNull(pw, "SA_PASSWORD must be set");
container.withPassword(pw);
Defensive patterns

Strategy: validation

Validate before calling

if (password == null) { throw new IllegalStateException("SA password must be set before withPassword()"); }

Type guard

boolean hasPassword = password != null && !password.isBlank();

Try / catch

try { container.withPassword(pw); } catch (IllegalArgumentException e) { throw new IllegalStateException("Invalid SA password config: " + e.getMessage(), e); }

Prevention

When it happens

Trigger: Calling withPassword(null) on modules/mssqlserver MSSQLServerContainer, or passing a variable that was never initialized / loaded from a null config value.

Common situations: Password read from a properties/env loader that returns null when the key is absent; test fixtures where the password field is left unset; refactors that renamed the config key.

Related errors

AI-assisted analysis of testcontainers/testcontainers-java@8e549514e3 (2026-09-12). Data as JSON: /api/errors/0cdf5d7685f4925c. Report an issue: GitHub.

Appendix: source

Thrown at modules/mssqlserver/src/main/java/org/testcontainers/containers/MSSQLServerContainer.java:142

    public String getPassword() {
        return password;
    }

    @Override
    public String getTestQueryString() {
        return "SELECT 1";
    }

    @Override
    public SELF withPassword(final String password) {
        checkPasswordStrength(password);
        this.password = password;
        return self();
    }

    private void checkPasswordStrength(String password) {
        if (password == null) {
            throw new IllegalArgumentException("Null password is not allowed");
        }

        if (password.length() < 8) {
            throw new IllegalArgumentException("Password should be at least 8 characters long");
        }

        if (password.length() > 128) {
            throw new IllegalArgumentException("Password can be up to 128 characters long");
        }

        long satisfiedCategories = Stream
            .of(PASSWORD_CATEGORY_VALIDATION_PATTERNS)
            .filter(p -> p.matcher(password).find())
            .count();

        if (satisfiedCategories < 3) {
            throw new IllegalArgumentException(
                "Password must contain characters from three of the following four categories:\n" +

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