> ## Documentation Index
> Fetch the complete documentation index at: https://docs.pipecat.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Exceptions

> Error handling hierarchy for Pipecat Flows

## Overview

Pipecat Flows defines a hierarchy of exceptions for handling errors during flow execution. All exceptions inherit from `FlowError`, making it possible to catch all flow-related errors with a single handler.

```python theme={null}
from pipecat_flows import (
    FlowError,
    FlowInitializationError,
    FlowTransitionError,
    InvalidFunctionError,
    ActionError,
)
```

## Exception Hierarchy

```
FlowError
├── FlowInitializationError
├── FlowTransitionError
├── InvalidFunctionError
└── ActionError
```

## FlowError

```python theme={null}
class FlowError(Exception)
```

Base exception for all flow-related errors. Use this for generic flow errors or as a catch-all for any flow exception.

```python theme={null}
try:
    await flow_manager.initialize(initial_node)
except FlowError as e:
    logger.error(f"Flow error: {e}")
```

## FlowInitializationError

```python theme={null}
class FlowInitializationError(FlowError)
```

Raised when flow manager initialization fails. Common causes include invalid configuration, missing dependencies, or calling `initialize()` with an invalid node config.

**Raised by:** `FlowManager.initialize()`

## FlowTransitionError

```python theme={null}
class FlowTransitionError(FlowError)
```

Raised when a node transition fails. This typically occurs when attempting to transition before the flow manager is initialized, or when a target node configuration is invalid.

**Raised by:** `FlowManager.set_node_from_config()`, internal node transition logic

## InvalidFunctionError

```python theme={null}
class InvalidFunctionError(FlowError)
```

Raised when a function cannot be registered or executed. Common causes include functions not found in the main module, invalid function signatures, direct functions that don't return a tuple, or missing docstrings on direct functions.

**Raised by:** Function registration, `FlowsDirectFunctionWrapper.validate_function()`

## ActionError

```python theme={null}
class ActionError(FlowError)
```

Raised when an action execution fails. This includes both built-in actions (`tts_say`, `end_conversation`, `function`) and custom registered actions. Common causes include missing required fields (e.g., `text` for `tts_say`), unregistered action types, or handler execution errors.

**Raised by:** `ActionManager.execute_actions()`, action handler registration