ellite/Wallos · error · Exception

$this->lang('encoding') . $encoding

Error message

$this->lang('encoding') . $encoding

What it means

addAttachment() throws lang('encoding') plus the given encoding string when validateEncoding() rejects the $encoding argument. Only the constants PHPMailer supports (7bit, 8bit, base64, binary, quoted-printable) are accepted for attachments.

Solutions

  1. Use the class constants: PHPMailer::ENCODING_BASE64, ENCODING_7BIT, ENCODING_8BIT, ENCODING_BINARY, ENCODING_QUOTED_PRINTABLE
  2. Remove the explicit encoding argument and rely on the default (base64)
  3. Check for typos/case: the accepted values are lowercase exact strings

Example fix

// before
$mail->addAttachment($path, 'report.pdf', 'base-64');
// after
$mail->addAttachment($path, 'report.pdf', PHPMailer::ENCODING_BASE64);
Defensive patterns

Strategy: type-guard

Validate before calling

$allowed = [PHPMailer::ENCODING_7BIT, PHPMailer::ENCODING_8BIT, PHPMailer::ENCODING_BASE64, PHPMailer::ENCODING_BINARY, PHPMailer::ENCODING_QUOTED_PRINTABLE];
if (!in_array($encoding, $allowed, true)) { throw new InvalidArgumentException("Unsupported attachment encoding: $encoding"); }

Type guard

function isValidMailEncoding($e): bool { return is_string($e) && in_array($e, ['7bit','8bit','base64','binary','quoted-printable'], true); }

Try / catch

try { $mail->addAttachment($path, $name, $encoding); } catch (PHPMailer\PHPMailer\Exception $e) { if (str_contains($e->getMessage(), 'encoding')) { $mail->addAttachment($path, $name, PHPMailer::ENCODING_BASE64); } else { throw $e; } }

Prevention

When it happens

Trigger: Passing an unsupported encoding such as 'base 64', 'BASE64', 'utf-8', or a typo to addAttachment($path, $name, $encoding).

Common situations: Developers confusing content encoding with charset and passing 'utf-8' or 'iso-8859-1'; hand-typed 'base64' vs the constant is fine, but misspellings like 'base-64' fail.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

AI-assisted analysis of ellite/Wallos@52820e87ca (2026-09-13). Data as JSON: /api/errors/b7db2bcbb6a448d7. Report an issue: GitHub.

Appendix: source

Thrown at libs/PHPMailer/PHPMailer.php:3241

        $type = '',
        $disposition = 'attachment'
    ) {
        try {
            if (!static::fileIsAccessible($path)) {
                throw new Exception($this->lang('file_access') . $path, self::STOP_CONTINUE);
            }

            //If a MIME type is not specified, try to work it out from the file name
            if ('' === $type) {
                $type = static::filenameToType($path);
            }

            $filename = (string) static::mb_pathinfo($path, PATHINFO_BASENAME);
            if ('' === $name) {
                $name = $filename;
            }
            if (!$this->validateEncoding($encoding)) {
                throw new Exception($this->lang('encoding') . $encoding);
            }

            $this->attachment[] = [
                0 => $path,
                1 => $filename,
                2 => $name,
                3 => $encoding,
                4 => $type,
                5 => false, //isStringAttachment
                6 => $disposition,
                7 => $name,
            ];
        } catch (Exception $exc) {
            $this->setError($exc->getMessage());
            $this->edebug($exc->getMessage());
            if ($this->exceptions) {
                throw $exc;
            }

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