symfony/routing · error · RuntimeException

Using "%% %%" is not allowed in routing configuration.

Error message

Using "%%%s%%" is not allowed in routing configuration.

What it means

Routing configuration is compiled and cached, so it must not contain raw %env(...)%% parameter placeholders (env vars are not available at route-compile time in production). The Router's parameter resolver rejects any %env(...)% placeholder found in routing values.

Solutions

1. Remove the %env(...)% placeholder from the routing configuration.
2. Move the env-dependent value into a container parameter (parameters.yaml binds env) and reference %parameter_name% instead.
3. Use a route loader/condition or runtime requirement that evaluates env at request time rather than compile time.
4. Keep the resolved parameter from itself containing an env placeholder chain to also avoid error [3].

Example fix

// before (routes.yaml)
host: '%env(APP_HOST)%'
// after
# config/packages/app.yaml: parameters: app_host: '%env(APP_HOST)%'
host: '%app_host%'

if (preg_match('/%env\(/', $routeValue)) {
    throw new LogicException('Route configuration must not contain %env(...)% placeholders.');
}

try { $url = $generator->generate($name, $params); } catch (RuntimeException $e) { // env placeholder in routing config
    throw new ConfigException('Fix routing config: '.$e->getMessage());
}

When it happens

Trigger: A route definition (path, host, defaults, requirements) contains a placeholder like '%env(APP_SECRET)%' which Router::resolve matches while expanding %...% parameters.

Common situations: Copy-pasting container config syntax into routes.yaml; trying to read env vars in route hosts/defaults; framework.version upgrades surfacing legacy env placeholders in route files.

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

• The container parameter
• The container parameter
• Unable to generate a URL for the named route
• Target route " " for alias " " does not exist.
• Unable to generate a URL for the named route

AI-assisted analysis of symfony/routing@83fa223250 (2026-09-14). Data as JSON: /api/errors/a66a0d908bd779a9. Report an issue: GitHub.

Appendix: source

Thrown at DependencyInjection/Router.php:175

            foreach ($value as $key => $val) {
                $value[$key] = $this->resolve($val);
            }

            return $value;
        }

        if (!\is_string($value)) {
            return $value;
        }

        $escapedValue = preg_replace_callback('/%%|%([^%\s]++)%/', function ($match) use ($value) {
            // skip %%
            if (!isset($match[1])) {
                return '%%';
            }

            if (preg_match('/^env\((?:\w++:)*+\w++\)$/', $match[1])) {
                throw new RuntimeException(\sprintf('Using "%%%s%%" is not allowed in routing configuration.', $match[1]));
            }

            $resolved = ($this->paramFetcher)($match[1]);

            if (\is_string($resolved) && preg_match('/env_[a-f0-9]{16}_\w+_[a-f0-9]{32}/Ui', $resolved)) {
                throw new RuntimeException(\sprintf('The container parameter "%s" resolves to an env var, which is not allowed in routing configuration.', $match[1]));
            }

            if (\is_scalar($resolved)) {
                $this->collectedParameters[$match[1]] = $resolved;

                if (\is_string($resolved)) {
                    $resolved = $this->resolve($resolved);
                }

                if (\is_scalar($resolved)) {
                    return false === $resolved ? '0' : (string) $resolved;
                }

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