laravel/framework · error · InvalidArgumentException

Index name contains invalid characters.

Error message

Index name contains invalid characters.

What it means

MySqlGrammar's compileIndexHint validates each comma-separated index name against /^[a-zA-Z0-9_$]+$/ before emitting USE INDEX / FORCE INDEX / IGNORE INDEX clauses. If any index name contains characters outside that set (spaces, hyphens, dots, backticks, etc.), an InvalidArgumentException is thrown before SQL compilation.

Solutions

1. Rename the index in the migration to use only alphanumeric, underscore, and dollar-sign characters
2. Remove invalid characters from the index hint string: replace hyphens, spaces, and dots with underscores
3. If the index genuinely contains special characters, reference it via a raw SQL clause instead of the index hint API

Example fix

// before — hyphen in index name throws
DB::table('orders')->forceIndex('order-status-idx')->where('status', 'pending')->get();

// after — underscore-only name passes
DB::table('orders')->forceIndex('order_status_idx')->where('status', 'pending')->get();

$indexName = 'user_email_idx';
if (preg_match('/^[a-zA-Z0-9_$]+$/', $indexName)) {
    DB::table('users')->forceIndex($indexName)->get();
} else {
    throw new \InvalidArgumentException("Invalid index name: {$indexName}");
}

function isValidIndexName(string $name): bool {
    return (bool) preg_match('/^[a-zA-Z0-9_$]+$/', $name);
}

try {
    DB::table('users')->forceIndex($indexName)->get();
} catch (\InvalidArgumentException $e) {
    if (str_contains($e->getMessage(), 'invalid characters')) {
        $sanitized = preg_replace('/[^a-zA-Z0-9_$]/', '_', $indexName);
        DB::table('users')->forceIndex($sanitized)->get();
    } else {
        throw $e;
    }
}

When it happens

Trigger: Calling ->from('table', 'bad name') with an invalid index hint, or ->forceIndex('my-index'), ->useIndex('col.idx'), or any index hint method where the index name contains characters other than letters, digits, underscores, or dollar signs.

Common situations: Passing a hyphenated index name (e.g., 'user_email_index' is fine but 'user-email-index' is not). Including backtick-quoted or schema-qualified names. Copying index names from migration output that contain unusual characters.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Index name contains invalid characters.
• Index name contains invalid characters.
• The seed value must be numeric.
• This database driver does not support the vector type.
• This database engine does not support JSON overlaps…

AI-assisted analysis of laravel/framework@e0f6eb3518 (2026-08-11). Data as JSON: /api/errors/528d2a2a5caaf943. Report an issue: GitHub.

Appendix: source

Thrown at src/Illuminate/Database/Query/Grammars/MySqlGrammar.php:153

    /**
     * Compile the index hints for the query.
     *
     * @param  \Illuminate\Database\Query\Builder  $query
     * @param  \Illuminate\Database\Query\IndexHint  $indexHint
     * @return string
     *
     * @throws \InvalidArgumentException
     */
    protected function compileIndexHint(Builder $query, $indexHint)
    {
        $index = $indexHint->index;

        $indexes = array_map('trim', explode(',', $index));

        foreach ($indexes as $i) {
            if (! preg_match('/^[a-zA-Z0-9_$]+$/', $i)) {
                throw new InvalidArgumentException('Index name contains invalid characters.');
            }
        }

        return match ($indexHint->type) {
            'hint' => "use index ({$index})",
            'force' => "force index ({$index})",
            default => "ignore index ({$index})",
        };
    }

    /**
     * Compile a group limit clause.
     *
     * @param  \Illuminate\Database\Query\Builder  $query
     * @return string
     */
    protected function compileGroupLimit(Builder $query)
    {

View on GitHub (pinned to e0f6eb3518)