oraios/serena · error · ValueError

No symbol declaration found at the location of the regex mat

Error message

No symbol declaration found at the location of the regex match. Location: {relative_path}:{coords.line}:{coords.col}.

What it means

find_symbol by regex/coordinate flow locates a regex match in a file, then asks the language server for the symbol declaration at that position. If the language server reports no defining symbol at the match's line/column, the tool raises this ValueError.

Source

Thrown at src/serena/tools/symbol_tools.py:453

            coords = find_text_coordinates(content, regex, require_unique=True)
            assert coords is not None
        else:
            symbol = symbol_retriever.find_unique(name_path_pattern=containing_symbol_name_path, within_relative_path=relative_path)
            body_line_numers = symbol.get_body_line_numbers_or_raise()
            content = editor.read_file(relative_path, lines=body_line_numers)
            coords = find_text_coordinates(content, regex, require_unique=True)
            assert coords is not None
            coords.line += body_line_numers[0]

        # retrieve declaration
        defining_symbol = symbol_retriever.find_declaration(
            relative_file_path=relative_path,
            line=coords.line,
            column=coords.col,
            include_body=include_body,
        )
        if defining_symbol is None:
            raise ValueError(
                f"No symbol declaration found at the location of the regex match. Location: {relative_path}:{coords.line}:{coords.col}."
            )

        # create output
        symbol_dict = self._defining_symbol_to_result_dict(
            symbol_retriever,
            defining_symbol,
            include_body,
            include_info,
        )
        result = self._to_json(symbol_dict)
        return result

    @staticmethod
    def _defining_symbol_to_result_dict(
        symbol_retriever: Any,
        defining_symbol: LanguageServerSymbol,
        include_body: bool,

View on GitHub (pinned to 7fcbca7e62)

Solutions

Tighten the regex so matches land on actual symbol identifiers/declarations
Re-run the search immediately before symbol lookup so coordinates are current
Verify the file is in an LS-supported language and the symbol is a real declaration, not a comment/string
Fall back to find_symbol with a name_path_pattern instead of coordinate-based lookup

Example fix

// before
pattern = 'def'  # matches the word anywhere, incl. comments
// ValueError: No symbol declaration found at ...

// after
pattern = r'def\s+my_function\b'  # match lands on the actual symbol

Defensive patterns

Strategy: try-catch

Validate before calling

m = regex.search(text)
line = text.count('\n', 0, m.start()) + 1
col = m.start() - text.rfind('\n', 0, m.start())
# ensure match lands on an identifier, not comments/strings:
if text[m.start():m.end()] not in identifiers_of_file(text):
    raise SkipToolCall('regex match is not a symbol')

Try / catch

try:
    sym = find_symbol_by_regex_tool.apply(regex=pattern, ...)
except ValueError as e:
    if 'No symbol declaration found' in str(e):
        sym = find_symbol_tool.apply(name_path_pattern=extract_identifier(pattern))
    else:
        raise

Prevention

Anchor regexes to symbol declarations (e.g. r'def\\s+name\\b'), not bare keywords
Re-read the file right before coordinate lookup to avoid stale positions
Prefer name_path_pattern lookup over regex-coordinate lookup when possible

When it happens

Trigger: The regex matches text that is not a symbol declaration/usage the LS recognizes (comments, strings, keywords, generated code without LS support); the match's coordinates are stale after the file changed; the file's language has no active language server.

Common situations: Regex like 'def |class ' catching decorators or docstrings; file edited between pattern search and symbol lookup so line:col now lands elsewhere; searching in a file type the LS can't index.

Related errors

AI-assisted analysis of oraios/serena@7fcbca7e62 (2026-08-29). Data as JSON: /api/errors/598430963f2f9920. Report an issue: GitHub.