What causes "Failed to slice image" in Intervention/image?

Clamp arguments against the real frame count before slicing: offset into [0, count-1] and length into [1, count-offset].

Intervention/image · error · Intervention\Image\Exceptions\DriverException

Failed to slice image

Error message

Failed to slice image

What it means

Core::slice($offset, $length) deletes every frame outside the window [$offset, $offset+$length) and then rebuilds the list via coalesceImages(). ImagickException during that surgery — most often because the window covers zero frames (offset beyond the frame count, or length 0), which removes every image and leaves getImageIterations()/coalesceImages() running against an empty Imagick — is wrapped as this DriverException.

Source

Thrown at src/Drivers/Imagick/Core.php:163

    /**
     * {@inheritdoc}
     *
     * @see CollectionInterface::slice()
     *
     * @throws DriverException
     */
    public function slice(int $offset, ?int $length = null): CollectionInterface
    {
        $length = is_null($length) ? $this->count() : $length;
        $count = $this->count();

        for ($i = $count - 1; $i >= 0; $i--) {
            if ($i < $offset || $i >= $offset + $length) {
                try {
                    $this->imagick->setIteratorIndex($i);
                    $this->imagick->removeImage();
                } catch (ImagickException $e) {
                    throw new DriverException('Failed to slice image', previous: $e);
                }
            }
        }

        try {
            $loops = $this->imagick->getImageIterations();
            $coalesced = $this->imagick->coalesceImages();
            $this->imagick->clear();
            $this->imagick = $coalesced;
            $this->imagick->setImageIterations($loops);
        } catch (ImagickException $e) {
            throw new DriverException('Failed to slice image', previous: $e);
        }

        return $this;
    }

    /**

View on GitHub (pinned to 5598b9e397)

Solutions

Clamp arguments against the real frame count before slicing: offset into [0, count-1] and length into [1, count-offset].
Validate the requested window against $image->core()->count() and reject nonsensical ranges upstream.
For huge GIFs, raise memory_limit or reduce frame count before slicing so coalesceImages() can complete.

Example fix

// before
$image->core()->slice(5, 3); // gif only has 4 frames → all frames removed → Imagick error

// after
$count = $image->core()->count();
$offset = max(0, min(5, $count - 1));
$length = max(1, min(3, $count - $offset));
$image->core()->slice($offset, $length);

Defensive patterns

Strategy: validation

Validate before calling

$count = $image->core()->count();
$offset = max(0, min($offset, $count - 1));
$length = max(1, min($length, $count - $offset));
$image->core()->slice($offset, $length);

Try / catch

try { $image->core()->slice($offset, $length); } catch (DriverException $e) { /* usually a degenerate window: validate against count() and retry with clamped values */ }

Prevention

Always clamp offset/length against the live frame count before slicing.
Validate animation-trimming parameters from user input against count().
Remember a window covering zero frames empties the Imagick container and fails.

When it happens

Trigger: slice($offset, $length) with offset >= frame count or length <= 0; slicing a single-frame image to nothing; very large GIFs where coalesceImages() exhausts memory mid-rebuild.

Common situations: Animation trimming code computing offset/length from unvalidated user input; GIF batch pipelines; slicing after frame removal shifted the count.

Related errors

AI-assisted analysis of Intervention/image@5598b9e397 (2026-08-23). Data as JSON: /api/errors/1a4842f0e3cbf082. Report an issue: GitHub.