Aider-AI/aider · error · DiffError

Add File action missing path.

Error message

Add File action missing path.

What it means

Parser error from PatchCoder when an '*** Add File:' header line carries no path. Symmetric to the Delete variant: the text after the prefix must be a non-empty path before an ADD PatchAction can be created.

Source

Thrown at aider/coders/patch_coder.py:383

                        # Duplicate delete – ignore the extra block
                        self.io.tool_warning(f"Duplicate delete action for file: {path} ignored.")
                        continue
                    else:
                        raise DiffError(f"Conflicting actions for file: {path}")
                if path not in current_files:
                    raise DiffError(
                        f"Delete File Error - file not found: {path}"
                    )  # Check against known files

                patch.actions[path] = PatchAction(type=ActionType.DELETE, path=path)
                continue

            # ---------- ADD ---------- #
            elif norm_line.startswith("*** Add File: "):
                path = norm_line[len("*** Add File: ") :].strip()
                index += 1
                if not path:
                    raise DiffError("Add File action missing path.")
                if path in patch.actions:
                    raise DiffError(f"Duplicate action for file: {path}")
                # Check if file exists in the context provided (should not for Add).
                # Note: We only have needed files, a full check requires FS access.
                # if path in current_files:
                #     raise DiffError(f"Add File Error - file already exists: {path}")

                action, index = self._parse_add_file_content(lines, index)
                action.path = path  # Ensure path is set
                patch.actions[path] = action
                continue

            # If we are here, the line is unexpected
            # Allow blank lines between actions
            if not norm_line.strip():
                index += 1
                continue

View on GitHub (pinned to 5dc9490bb3)

Solutions

1. Regenerate with a complete '*** Add File: <relative/path>' header
2. Raise the model's max output tokens if truncation is the cause
3. Pre-validate patch headers programmatically before handing text to PatchCoder

Example fix

// before
*** Add File: 
+content

// after
*** Add File: src/new_module.py
+content

import re
ADD_HDR = re.compile(r"^\*\*\* Add File: (.+)$")

def add_headers_valid(patch_text: str) -> bool:
    return all(ADD_HDR.match(l) is not None
               for l in patch_text.splitlines()
               if l.startswith("*** Add File"))

try:
    edits = coder.get_edits(reply)
except DiffError as e:
    if "Add File action missing path" in str(e):
        edits = coder.get_edits(regenerate_patch(reply))
    else:
        raise

When it happens

Trigger: Model output contains '*** Add File: ' with a blank filename, or the header was truncated by a token/streaming limit before the filename was emitted.

Common situations: Output truncation near max_tokens; models unfamiliar with the patch format omitting the filename; whitespace-only paths from sloppy prompt templates.

Related errors

• Delete File action missing path.
• Bad/missing filename. The filename must be alone on the line
• Expected `=======`
• Expected `>>>>>>> REPLACE` or `=======`
• Duplicate action for file: {path}

AI-assisted analysis of Aider-AI/aider@5dc9490bb3 (2026-08-15). Data as JSON: /api/errors/99ec75d74b026dc4. Report an issue: GitHub.