What causes "Empty path segments not allowed in subfolder path" in invoke-ai/InvokeAI?

Normalize the subfolder with posixpath.normpath before calling

Empty path segments not allowed in subfolder path

Error message

Empty path segments not allowed in subfolder path

What it means

Empty segments in the subfolder (e.g. 'a//b', 'a/', or leading '/') are rejected to keep paths canonical and avoid ambiguity in storage layout. Raises ValueError('Empty path segments not allowed in subfolder path').

Source

Thrown at invokeai/app/services/image_files/image_files_disk.py:291

            raise ValueError("Image path outside outputs folder, potential directory traversal detected")

        return resolved_image_path

    @staticmethod
    def _validate_subfolder(subfolder: str) -> None:
        """Validates a subfolder path to prevent directory traversal while allowing controlled subdirectories."""
        if not subfolder:
            return
        if "\\" in subfolder:
            raise ValueError("Backslashes not allowed in subfolder path")
        if subfolder.startswith("/"):
            raise ValueError("Absolute paths not allowed in subfolder path")
        parts = subfolder.split("/")
        for part in parts:
            if part == "..":
                raise ValueError("Parent directory references not allowed in subfolder path")
            if part == "":
                raise ValueError("Empty path segments not allowed in subfolder path")

    def validate_path(self, path: Union[str, Path]) -> bool:
        """Validates the path given for an image or thumbnail."""
        path = path if isinstance(path, Path) else Path(path)
        return path.exists()

    def get_workflow(self, image_name: str, image_subfolder: str = "") -> str | None:
        image = self.get(image_name, image_subfolder=image_subfolder)
        workflow = image.info.get("invokeai_workflow", None)
        if isinstance(workflow, str):
            return workflow
        return None

    def get_graph(self, image_name: str, image_subfolder: str = "") -> str | None:
        image = self.get(image_name, image_subfolder=image_subfolder)
        graph = image.info.get("invokeai_graph", None)
        if isinstance(graph, str):
            return graph

View on GitHub (pinned to 0b6a024f2f)

Solutions

Normalize the subfolder with posixpath.normpath before calling
Filter out empty parts: '/'.join(p for p in sub.split('/') if p)
Reject or strip trailing/leading slashes at your API boundary

Example fix

// before
sub = board + '/'  # 'myboard/'
// after
sub = '/'.join(p for p in sub.split('/') if p)

Defensive patterns

Strategy: validation

Validate before calling

import posixpath
def canonical_subfolder(s: str) -> str:
    return posixpath.normpath(s.strip('/'))
sub = canonical_subfolder(sub)
assert '' not in sub.split('/')

Type guard

def has_no_empty_segments(s: object) -> bool:
    return isinstance(s, str) and s != '' and all(p for p in s.split('/'))

Try / catch

try:
    service.get(name, image_subfolder=subfolder)
except ValueError as e:
    if 'Empty path segments' in str(e):
        subfolder = '/'.join(p for p in subfolder.split('/') if p)
        service.get(name, image_subfolder=subfolder)

Prevention

Normalize subfolders with posixpath.normpath before every call
Strip leading/trailing slashes from user input
Avoid hand-concatenating path fragments with '/'

When it happens

Trigger: Passing image_subfolder like 'a//b', 'a/', or '' handled after the falsy check (non-empty but with empty segments); joining strings with trailing separators.

Common situations: String-concatenating subfolder parts with stray slashes; splitting/rejoining paths from user input; trailing slash from URL parsing.

Related errors

AI-assisted analysis of invoke-ai/InvokeAI@0b6a024f2f (2026-08-29). Data as JSON: /api/errors/b20fadb4c9e7562e. Report an issue: GitHub.