# Source: https://gofastmcp.com/python-sdk/fastmcp-exceptions.md

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# exceptions

# `fastmcp.exceptions`

Custom exceptions for FastMCP.

## Classes

### `FastMCPError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L6" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Base error for FastMCP.

### `ValidationError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L10" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Error in validating parameters or return values.

### `ResourceError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L14" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Error in resource operations.

### `ToolError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L18" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Error in tool operations.

### `PromptError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L22" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Error in prompt operations.

### `InvalidSignature` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L26" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Invalid signature for use with FastMCP.

### `ClientError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L30" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Error in client operations.

### `NotFoundError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L34" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Object not found.

### `DisabledError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L38" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Object is disabled.

### `AuthorizationError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/exceptions.py#L42" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

Error when authorization check fails.