Enum Error 

pub enum Error {
    Connection(String),
    ConnectionClosed,
    Authentication(AuthError),
    Tls(String),
    Protocol(String),
    Codec(CodecError),
    Type(TypeError),
    Query(String),
    Server {
        number: i32,
        class: u8,
        state: u8,
        message: String,
        server: Option<String>,
        procedure: Option<String>,
        line: u32,
    },
    Transaction(String),
    Config(String),
    ConnectTimeout,
    TlsTimeout,
    ConnectionTimeout,
    CommandTimeout,
    Routing {
        host: String,
        port: u16,
    },
    TooManyRedirects {
        max: u8,
    },
    Io(Arc<Error>),
    InvalidIdentifier(String),
    PoolExhausted,
}

Errors that can occur during client operations.

Variants

Connection(String)

Connection failed.

ConnectionClosed

Connection closed unexpectedly.

Authentication(AuthError)

Authentication failed.

Tls(String)

TLS error (string for flexibility in connection code).

Protocol(String)

Protocol error (string for flexibility in connection code).

Codec(CodecError)

Codec error.

Type(TypeError)

Type conversion error.

Query(String)

Query execution error.

Server

Server returned an error.

Fields

number: i32

Error number.

class: u8

Error class/severity (0-25).

state: u8

Error state.

message: String

Error message.

server: Option<String>

Server name where error occurred.

procedure: Option<String>

Stored procedure name (if applicable).

line: u32

Line number in the SQL batch or procedure.

Transaction(String)

Transaction error.

Config(String)

Configuration error.

ConnectTimeout

TCP connection timeout occurred.

TlsTimeout

TLS handshake timeout occurred.

ConnectionTimeout

Connection timeout occurred (alias for backwards compatibility).

CommandTimeout

Command execution timeout occurred.

Routing

Connection routing required (Azure SQL).

Fields

host: String

Target host.

port: u16

Target port.

TooManyRedirects

Too many redirects during connection.

Fields

max: u8

Maximum redirects allowed.

Io(Arc<Error>)

IO error (wrapped in Arc for Clone support).

InvalidIdentifier(String)

Invalid identifier (potential SQL injection attempt).

PoolExhausted

Connection pool exhausted.

Implementations

impl Error

pub fn is_transient(&self) -> bool

Check if this error is transient and may succeed on retry.

Transient errors include timeouts, connection issues, and certain server errors that may resolve themselves.

Per ADR-009, the following server error codes are considered transient:

• 1205: Deadlock victim
• -2: Timeout
• 10928, 10929: Resource limit (Azure)
• 40197: Service error (Azure)
• 40501: Service busy (Azure)
• 40613: Database unavailable (Azure)
• 49918, 49919, 49920: Cannot process request (Azure)
• 4060: Cannot open database (may be transient during failover)
• 18456: Login failed (may be transient in Azure during failover)

pub fn is_transient_server_error(number: i32) -> bool

Check if a server error number is transient (may succeed on retry).

This follows the error codes specified in ADR-009.

pub fn is_terminal(&self) -> bool

Check if this is a terminal error that will never succeed on retry.

Terminal errors include syntax errors, constraint violations, and other errors that indicate programmer error or data issues.

Per ADR-009, the following server error codes are terminal:

• 102: Syntax error
• 207: Invalid column
• 208: Invalid object
• 547: Constraint violation
• 2627: Unique constraint violation
• 2601: Duplicate key

pub fn is_terminal_server_error(number: i32) -> bool

Check if a server error number is terminal (will never succeed on retry).

This follows the error codes specified in ADR-009.

pub fn is_protocol_error(&self) -> bool

Check if this error indicates a protocol/driver bug.

Protocol errors typically indicate a bug in the driver implementation rather than a user error or server issue.

pub fn is_server_error(&self, number: i32) -> bool

Check if this is a server error with a specific number.

pub fn class(&self) -> Option<u8>

Get the error class/severity if this is a server error.

SQL Server error classes range from 0-25:

• 0-10: Informational
• 11-16: User errors
• 17-19: Resource/hardware errors
• 20-25: System errors (connection terminating)

pub fn severity(&self) -> Option<u8>

Alias for class() - returns error severity.

Trait Implementations

impl Debug for Error

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Error

fn fmt(&self, __formatter: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl From<AuthError> for Error

fn from(source: AuthError) -> Self

Converts to this type from the input type.

impl From<CodecError> for Error

fn from(source: CodecError) -> Self

Converts to this type from the input type.

impl From<Error> for Error

fn from(e: Error) -> Self

Converts to this type from the input type.

impl From<ProtocolError> for Error

fn from(e: ProtocolError) -> Self

Converts to this type from the input type.

impl From<TlsError> for Error

fn from(e: TlsError) -> Self

Converts to this type from the input type.

impl From<TypeError> for Error

fn from(source: TypeError) -> Self

Converts to this type from the input type.