invoke-ai/InvokeAI · error

Duplicate destination thumbnail path: {move.new_thumbnail_pa

Error message

Duplicate destination thumbnail path: {move.new_thumbnail_path}

What it means

Analogous to duplicate image destinations, two moves in one batch must not claim the same thumbnail destination. preflight_moves tracks new_thumbnail_path values and raises ValueError on a repeat, since each image's thumbnail must land in a unique file.

Source

Thrown at invokeai/app/services/image_moves/image_moves_default.py:442

            return job_id

    def preflight_moves(self, moves: Sequence[PlannedImageMove]) -> None:
        destinations: set[Path] = set()
        thumbnail_destinations: set[Path] = set()
        for move in moves:
            if not move.old_path.exists():
                if not move.is_intermediate:
                    raise FileNotFoundError(f"Source image does not exist: {move.old_path}")
                continue
            if move.new_path.exists():
                raise FileExistsError(f"Destination image already exists: {move.new_path}")
            if move.old_path == move.new_path:
                raise ValueError(f"Old and new paths are identical for {move.image_name}")
            if move.new_path in destinations:
                raise ValueError(f"Duplicate destination path: {move.new_path}")
            destinations.add(move.new_path)
            if move.new_thumbnail_path in thumbnail_destinations:
                raise ValueError(f"Duplicate destination thumbnail path: {move.new_thumbnail_path}")
            thumbnail_destinations.add(move.new_thumbnail_path)
            if self._has_active_job_for_image(move.image_name):
                raise ValueError(f"Image {move.image_name} already has an active image move job")
            self._assert_same_filesystem(move.old_path, move.new_path)
            if move.old_thumbnail_path.exists():
                if move.new_thumbnail_path.exists():
                    raise FileExistsError(f"Destination thumbnail already exists: {move.new_thumbnail_path}")
                self._assert_same_filesystem(move.old_thumbnail_path, move.new_thumbnail_path)

    def _record_missing_source_errors(self, moves: Sequence[PlannedImageMove]) -> tuple[list[PlannedImageMove], int]:
        remaining_moves: list[PlannedImageMove] = []
        errors = 0
        for move in moves:
            if move.old_path.exists() or move.is_intermediate:
                remaining_moves.append(move)
                continue
            message = f"Source image does not exist: {move.old_path}"
            self.create_error_move_job(move, message)

View on GitHub (pinned to 0b6a024f2f)

Solutions

1. Ensure thumbnail destinations are derived from unique destination image paths
2. De-duplicate or suffix colliding thumbnail paths when planning
3. Filter/split batches so each new_thumbnail_path is unique before preflight

Example fix

// before
new_thumb = thumb_dir / img.name  # collides for duplicate names
// after
new_thumb = (dest_dir / img.name).with_suffix('.thumb.png')  # unique per destination

thumbs = [m.new_thumbnail_path for m in moves]
dupes = {t for t in thumbs if thumbs.count(t) > 1}
if dupes:
    raise ValueError(f"duplicate thumbnail destinations: {dupes}")
service.preflight_moves(moves)

def thumbnail_destinations_unique(moves: Sequence[PlannedImageMove]) -> bool:
    return len({m.new_thumbnail_path for m in moves}) == len(moves)

try:
    service.preflight_moves(moves)
except ValueError as e:
    if "Duplicate destination thumbnail path" in str(e):
        moves = rebuild_thumbnail_paths(moves)
        service.preflight_moves(moves)
    else:
        raise

When it happens

Trigger: Two distinct images whose planned thumbnail filenames collide (same name into same folder); constructing PlannedImageMove with hand-built thumbnail paths that repeat; batch merging folders with duplicate names where thumbnail naming derives only from the image name.

Common situations: Merging subfolders with identically named images; custom thumbnail-path generation ignoring the source directory; automated scripts generating moves for many folders into one.

Related errors

• Duplicate destination path: {move.new_path}
• LoRA "{lora_key}" already applied to transformer.
• LoRA "{lora_key}" already applied to transformer.
• Cannot create an image move job with no items
• Old and new paths are identical for {move.image_name}

AI-assisted analysis of invoke-ai/InvokeAI@0b6a024f2f (2026-08-29). Data as JSON: /api/errors/e1bd1dced45fea3a. Report an issue: GitHub.