Seldaek/monolog · error · InvalidArgumentException

The content type can not contain newline characters to preve

Error message

The content type can not contain newline characters to prevent email header injection

What it means

Error "The content type can not contain newline characters to prevent email header injection" thrown in Seldaek/monolog.

Source

Thrown at src/Monolog/Handler/NativeMailerHandler.php:152

    public function getContentType(): ?string
    {
        return $this->contentType;
    }

    public function getEncoding(): string
    {
        return $this->encoding;
    }

    /**
     * @param  string $contentType The content type of the email - Defaults to text/plain. Use text/html for HTML messages.
     * @return $this
     */
    public function setContentType(string $contentType): self
    {
        if (strpos($contentType, "\n") !== false || strpos($contentType, "\r") !== false) {
            throw new \InvalidArgumentException('The content type can not contain newline characters to prevent email header injection');
        }

        $this->contentType = $contentType;

        return $this;
    }

    /**
     * @return $this
     */
    public function setEncoding(string $encoding): self
    {
        if (strpos($encoding, "\n") !== false || strpos($encoding, "\r") !== false) {
            throw new \InvalidArgumentException('The encoding can not contain newline characters to prevent email header injection');
        }

        $this->encoding = $encoding;

View on GitHub (pinned to 57eb102834)

When it happens

Trigger: Thrown at src/Monolog/Handler/NativeMailerHandler.php:152 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Seldaek/monolog@57eb102834 (2026-08-17). Data as JSON: /api/errors/448fc1363f05eec3. Report an issue: GitHub.