Intervention/image · error · ImageDecoderException

Base64-encoded data contains unsupported image type

Error message

Base64-encoded data contains unsupported image type

What it means

Thrown by Base64ImageDecoder::decode when the Base64 decoding itself succeeded, but passing the resulting binary to BinaryImageDecoder::decode raised a DecoderException. The decoded payload is therefore not an image the GD driver can process — it is another file type, an unsupported image format, or corrupted image data.

Source

Thrown at src/Drivers/Gd/Decoders/Base64ImageDecoder.php:43

    }

    /**
     * {@inheritdoc}
     *
     * @see DecoderInterface::decode()
     */
    public function decode(mixed $input): ImageInterface
    {
        try {
            $data = $this->decodeBase64Data($input);
        } catch (DecoderException) {
            throw new ImageDecoderException('Unable to Base64-decode image from string');
        }

        try {
            return parent::decode($data);
        } catch (DecoderException) {
            throw new ImageDecoderException('Base64-encoded data contains unsupported image type');
        }
    }
}

View on GitHub (pinned to 5598b9e397)

Solutions

1. Decode and inspect the payload manually: $bin = base64_decode($s, true); var_dump(strlen($bin), substr($bin, 0, 16), @getimagesizefromstring($bin));
2. Verify the column/transport length (TEXT not VARCHAR(255)) and re-test with a fresh, known-good upload
3. Convert the source to PNG/JPEG client-side or in a pre-processing step if it is HEIC/TIFF/SVG
4. Wrap read() in try/catch on ImageDecoderException and return a validation error to the uploader

Example fix

// before
$image = $manager->read($request->input('image'));
// ImageDecoderException: Base64-encoded data contains unsupported image type

// after
$bin = base64_decode(preg_replace('/\s+/', '', $request->input('image')), true);
if ($bin === false || @getimagesizefromstring($bin) === false) {
    return back()->withErrors(['image' => 'Please upload a PNG, JPEG, GIF or WebP image.']);
}
$image = $manager->read(base64_encode($bin));

$bin = base64_decode(preg_replace('/\s+/', '', $b64), true);
if ($bin === false || $bin === '' || @getimagesizefromstring($bin) === false) {
    throw new RuntimeException('Base64 payload is not a decodable image');
}

try {
    $image = $manager->read($b64);
} catch (\Intervention\Image\Exceptions\ImageDecoderException $e) {
    // payload decoded but content is unsupported/corrupt; return validation error
    return response()->json(['error' => 'Unsupported image data'], 422);
}

When it happens

Trigger: ImageManager::read($base64String) where the payload decodes to a PDF/SVG/TIFF/HEIC, to a truncated PNG/JPEG (clipped upload), to an empty result, or to an image in a format this GD build cannot parse. The parent BinaryImageDecoder throws (empty string, imagecreatefromstring === false, or unmapped MIME) and it is re-wrapped as this ImageDecoderException.

Common situations: Base64 round-trips through JSON or databases that silently truncate long values (VARCHAR too short, cut multipart bodies); clients base64-encoding whatever file the user picked; HEIC photos from iPhones on servers without AVIF/HEIC handling; double-encoded payloads (base64 of base64).

Related errors

• Failed to decode unsupported image format from binary data
• Unsupported media type (MIME) ${mime}.
• File contains unsupported image format
• Failed to read media (MIME) type from binary data
• Unable to Base64-decode image from string

AI-assisted analysis of Intervention/image@5598b9e397 (2026-08-23). Data as JSON: /api/errors/e07d66842ecc35b1. Report an issue: GitHub.