# Error Reference

URL: /docs/reference/errors/
Section: reference
Tags: errors, exceptions, reference

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Error Hierarchy Pounce uses a structured error hierarchy for clear error messages: flowchart TD Base["PounceError\n(base)"] Base --> ConfigError["ConfigError\nInvalid configuration"] Base --> ImportError["ImportError\nApplication import failures"] Base --> ProtocolError["ProtocolError\nProtocol-level errors"] Base --> LifespanError["LifespanError\nASGI lifespan failures"] Base --> ShutdownError["ShutdownError\nShutdown-related issues"] Configuration Errors These occur at startup when ServerConfig validation fails: Error Cause host must be a non-empty string Empty host string port must be 0-65535 Port out of valid range workers must be >= 0 Negative worker count ssl_certfile and ssl_keyfile must both be set or both be None Only one TLS file provided log_level must be one of [...] Invalid log level string Import Errors Error Cause Could not import module 'X' Module not found or import error Module 'X' has no attribute 'Y' App attribute doesn't exist App 'X' is not callable Imported object isn't an ASGI callable Protocol Errors Error Cause Request too large Body exceeds max_request_size Too many headers Header count exceeds max_headers Header size exceeded Headers exceed max_header_size Request timeout Request not completed within request_timeout Lifespan Errors Error Cause Lifespan startup failed App sent lifespan.startup.failed Lifespan startup timed out App didn't respond to startup event Runtime Behavior Pounce follows the "fail loudly" principle: Configuration errors — Raised immediately at startup, before binding sockets Import errors — Raised before any workers start Protocol errors — Logged and connection closed gracefully Lifespan errors — Server exits with non-zero status See Also ServerConfig — Configuration validation rules Troubleshooting — Common issues and solutions

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