crewAIInc/crewAI · error · ValueError

Failed to load data from MySQL: {e}

Error message

Failed to load data from MySQL: {e}

What it means

Raised by MySQLLoader.load() for any non-pymysql exception during loading — the catch-all `except Exception` after the `except Error` clause. It typically fires before the DB is even reached: most commonly ModuleNotFoundError/ImportError because the module imports `connect`/`DictCursor`/`Error` from pymysql at import time in environments where pymysql is not installed, plus errors like URL parsing edge cases or dict/key errors while building connection params.

Source

Thrown at lib/crewai-tools/src/crewai_tools/rag/loaders/mysql_loader.py:102

                    if len(content) > 100000:
                        content = content[:100000] + "\n\n[Content truncated...]"

                    return LoaderResult(
                        content=content,
                        metadata={
                            "source": query,
                            "database": connection_params["database"],
                            "row_count": len(rows),
                            "columns": columns,
                        },
                        doc_id=self.generate_doc_id(source_ref=query, content=content),
                    )
            finally:
                connection.close()
        except Error as e:
            raise ValueError(f"MySQL database error: {e}") from e
        except Exception as e:
            raise ValueError(f"Failed to load data from MySQL: {e}") from e

View on GitHub (pinned to 754d7323be)

Solutions

1. Install the driver: pip install pymysql (or `pip install crewai-tools[rag]` / `uv add pymysql`).
2. Read the chained cause ({e}) — if it is ModuleNotFoundError the fix is the install above; otherwise address the specific underlying error.
3. Pin and sync the environment (uv sync / pip install -r) so pymysql survives rebuilds.

Example fix

# before
result = MySQLLoader().load(SourceContent('SELECT 1'), metadata={'db_uri': uri})  # ModuleNotFoundError wrapped

# after
# terminal: pip install pymysql
result = MySQLLoader().load(SourceContent('SELECT 1'), metadata={'db_uri': uri})

import importlib.util\n\ndef pymysql_available() -> bool:\n    return importlib.util.find_spec('pymysql') is not None

try:\n    result = MySQLLoader().load(src, metadata={'db_uri': uri})\nexcept ValueError as e:\n    if 'Failed to load data from MySQL' in str(e) and not pymysql_available():\n        raise RuntimeError('install pymysql: pip install pymysql') from e\n    raise

When it happens

Trigger: Importing/running MySQLLoader in an environment where pymysql is not installed (crewai-tools without the rag/DB extra); any unexpected exception while assembling parameters or formatting results that is not a pymysql.Error.

Common situations: Slim Docker/CI images without the optional database extras; assuming the loader uses SQLAlchemy (already installed) when it actually requires pymysql; environments where the dependency was pruned by a lockfile.

Related errors

• Database URI is required for MySQL loader
• Invalid MySQL URI scheme: {parsed.scheme}
• Database name is required in the URI
• MySQL database error: {e}
• Project name cannot be empty

AI-assisted analysis of crewAIInc/crewAI@754d7323be (2026-08-15). Data as JSON: /api/errors/d97176f49e15dbaa. Report an issue: GitHub.