symfony/http-foundation · error · LogicException

You cannot guess the mime type as the Mime component is not…

Error message

You cannot guess the mime type as the Mime component is not installed. Try running "composer require symfony/mime".

What it means

A LogicException thrown as a feature guard at the top of File::getMimeType(). It fires whenever the method is called but the symfony/mime package is absent (class_exists(MimeTypes::class) is false), meaning mime-type guessing cannot be performed at all; the environment is misconfigured, not the input.

Solutions

1. Install the Mime component: composer require symfony/mime
2. Wrap the call in class_exists(MimeTypes::class) check and skip or mock mime detection when the component is missing
3. Derive the type from the client-supplied Content-Type or a static extension map if symfony/mime cannot be added

When it happens

Trigger: Thrown at File/File.php:74 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of symfony/http-foundation@5aea19cd67 (2026-09-13). Data as JSON: /api/errors/51fb961c7c34385a. Report an issue: GitHub.

Appendix: source

Thrown at File/File.php:74

    public function guessExtension(): ?string
    {
        if (!class_exists(MimeTypes::class)) {
            throw new \LogicException('You cannot guess the extension as the Mime component is not installed. Try running "composer require symfony/mime".');
        }

        return MimeTypes::getDefault()->getExtensions($this->getMimeType())[0] ?? null;
    }

    /**
     * Returns the mime type of the file.
     *
     * The mime type is guessed using a MimeTypeGuesserInterface instance,
     * which uses finfo_file() then the "file" system binary,
     * depending on which of those are available.
     *
     * @see MimeTypes
     */
    public function getMimeType(): ?string
    {
        if (!class_exists(MimeTypes::class)) {
            throw new \LogicException('You cannot guess the mime type as the Mime component is not installed. Try running "composer require symfony/mime".');
        }

        return MimeTypes::getDefault()->guessMimeType($this->getPathname());
    }

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