twigphp/Twig · error · SyntaxError

When using set with a block, you cannot have a multi-target.

Error message

When using set with a block, you cannot have a multi-target.

What it means

The capture form of {% set %} ({% set name %}...{% endset %}) can only target a single variable. Multi-target capture is meaningless because the captured block produces one string, so Twig throws a syntax error.

Solutions

1. Capture into one variable, then derive the second: '{% set all %}...{% endset %}{% set a, b = all|split(',') %}'
2. Use two separate captured sets if the contents differ
3. Use the '=' form with equal counts instead of capture for multi-target assignment

Example fix

// before
{% set a, b %}hello{% endset %}
// after
{% set a %}hello{% endset %}{% set b = a ~ '!' %}

// Multi-target capture sets are invalid
if (preg_match('/\{%\s*set\s+[^=}%]*,[^=}%]*\s*%}(?:.|\n)*?\{%\s*endset\s*%}/', $src)) {
    throw new InvalidArgumentException('Capture form of set supports a single target.');
}

try {
    $twig->render($template, $ctx);
} catch (SyntaxError $e) {
    if (str_contains($e->getMessage(), 'multi-target')) {
        // rewrite template to single-target capture
    }
    throw $e;
}

When it happens

Trigger: Writing '{% set a, b %}...{% endset %}' — in parse, when no '=' follows the names and count($names) > 1, the error is raised.

Common situations: Converting a plain multi-target set ('{% set a, b = 1, 2 %}') into a captured block; misunderstanding capture semantics after seeing multi-target assignment elsewhere.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• When using set, you must have the same number of variables…
• Unexpected character
• The variadic argument
• The variadic argument
• The template references in a "use" statement must be a…

AI-assisted analysis of twigphp/Twig@a414c3a491 (2026-09-13). Data as JSON: /api/errors/fde3ac07a3dd3af1. Report an issue: GitHub.

Appendix: source

Thrown at src/TokenParser/SetTokenParser.php:53

    {
        $lineno = $token->getLine();
        $stream = $this->parser->getStream();
        $names = $this->parseAssignmentExpression();

        $capture = false;
        if ($stream->nextIf(Token::OPERATOR_TYPE, '=')) {
            $values = $this->parseMultitargetExpression();

            $stream->expect(Token::BLOCK_END_TYPE);

            if (\count($names) !== \count($values)) {
                throw new SyntaxError('When using set, you must have the same number of variables and assignments.', $stream->getCurrent()->getLine(), $stream->getSourceContext());
            }
        } else {
            $capture = true;

            if (\count($names) > 1) {
                throw new SyntaxError('When using set with a block, you cannot have a multi-target.', $stream->getCurrent()->getLine(), $stream->getSourceContext());
            }

            $stream->expect(Token::BLOCK_END_TYPE);

            $values = $this->parser->subparse([$this, 'decideBlockEnd'], true);
            $stream->expect(Token::BLOCK_END_TYPE);
        }

        return new SetNode($capture, $names, $values, $lineno);
    }

    public function decideBlockEnd(Token $token): bool
    {
        return $token->test('endset');
    }

    public function getTag(): string
    {

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