diff --git a/quinn-h3/Cargo.toml b/quinn-h3/Cargo.toml
index a8648236d..94d929278 100644
--- a/quinn-h3/Cargo.toml
+++ b/quinn-h3/Cargo.toml
@@ -26,7 +26,6 @@ maintenance = { status = "experimental" }
 
 [dependencies]
 bytes = "0.5.2"
-err-derive = "0.2.3"
 futures = "0.3.1"
 futures-util = { version = "0.3", default-features = false }
 http = "0.2"
@@ -36,6 +35,7 @@ pin-project = "^0.4.21"
 quinn-proto = { path = "../quinn-proto", version = "0.6.0" }
 quinn = { path = "../quinn", version = "0.6.0", features = ["tls-rustls"] }
 rustls = { git = "https://github.com/ctz/rustls", rev = "fee894f7e030", features = ["quic"] }
+thiserror = "1.0.21"
 tokio = "0.2.6"
 tokio-util = { version = "0.3.0", features = ["codec"] }
 tracing = "0.1.10"
diff --git a/quinn-h3/src/lib.rs b/quinn-h3/src/lib.rs
index ba6c3c927..3290c6d35 100644
--- a/quinn-h3/src/lib.rs
+++ b/quinn-h3/src/lib.rs
@@ -108,9 +108,9 @@ mod qpack;
 #[doc(hidden)]
 pub mod qpack;
 
-use err_derive::Error;
 use quinn::{ApplicationClose, ConnectionError, ReadError, StoppedError, VarInt, WriteError};
 use std::{error::Error as StdError, io::ErrorKind};
+use thiserror::Error;
 
 use proto::ErrorCode;
 
@@ -121,49 +121,49 @@ pub type ZeroRttAccepted = quinn::ZeroRttAccepted;
 #[derive(Debug, Error)]
 pub enum Error {
     /// Cannot make a new request, bescause the connection is closing
-    #[error(display = "Connection is closing, resquest aborted")]
+    #[error("Connection is closing, resquest aborted")]
     Aborted,
     /// Protocol violation detected by the internal HTTP/3 protocol state machine
-    #[error(display = "H3 protocol error: {:?}", _0)]
+    #[error("H3 protocol error: {0:?}")]
     Proto(proto::connection::Error),
     /// Error occurred at the `QUIC` level
-    #[error(display = "QUIC protocol error: {}", _0)]
+    #[error("QUIC protocol error: {0}")]
     Quic(quinn::ConnectionError),
     /// A `QUIC`-specific read error occurred
-    #[error(display = "QUIC read error: {}", _0)]
+    #[error("QUIC read error: {0}")]
     Read(ReadError),
     /// A `QUIC`-specific write error occurred
-    #[error(display = "QUIC write error: {}", _0)]
+    #[error("QUIC write error: {0}")]
     Write(WriteError),
     /// A `QUIC`-specific error occurred while polling for STOP_SENDING
-    #[error(display = "QUIC error while polling for STOP_SENDING: {}", _0)]
+    #[error("QUIC error while polling for STOP_SENDING: {0}")]
     Stopped(StoppedError),
     /// Programming error within the crate's code
-    #[error(display = "Internal error: {}", _0)]
+    #[error("Internal error: {0}")]
     Internal(String),
     /// The peer's behavior was detected as incorrect or malicious
-    #[error(display = "Incorrect peer behavior: {}", _0)]
+    #[error("Incorrect peer behavior: {0}")]
     Peer(String),
     /// The peer tried to open an unidirectional stream with an unknown type code
-    #[error(display = "unknown stream type {}", _0)]
+    #[error("unknown stream type {0}")]
     UnknownStream(u64),
     /// An IO error occurred
-    #[error(display = "IO error: {}", _0)]
+    #[error("IO error: {0}")]
     Io(std::io::Error),
     /// An overflow occurred into the `QPACK` decoder
-    #[error(display = "Overflow max data size")]
+    #[error("Overflow max data size")]
     Overflow,
     /// A future has been polled after it was already finished
-    #[error(display = "Polled after finished")]
+    #[error("Polled after finished")]
     Poll,
     /// The peer issued an HTTP/3 error code and an optional text description
-    #[error(display = "Http error: {:?}", _0)]
+    #[error("Http error: {0:?}")]
     Http(HttpError, Option<String>),
     /// Header validity error from a client call
-    #[error(display = "Header error: {:?}", _0)]
+    #[error("Header error: {0:?}")]
     Header(&'static str),
     /// Polling the issued body data yielded an error
-    #[error(display = "Polling body error: {}", _0)]
+    #[error("Polling body error: {0}")]
     Body(Box<dyn StdError + Send + Sync>),
 }
 
diff --git a/quinn-h3/src/qpack/decoder.rs b/quinn-h3/src/qpack/decoder.rs
index c395a8ebc..e80a52274 100644
--- a/quinn-h3/src/qpack/decoder.rs
+++ b/quinn-h3/src/qpack/decoder.rs
@@ -1,7 +1,7 @@
 use bytes::{Buf, BufMut};
 use std::{fmt, io::Cursor};
 
-use err_derive::Error;
+use thiserror::Error;
 use tracing::trace;
 
 use super::{
@@ -25,23 +25,23 @@ use super::{prefix_int, prefix_string};
 
 #[derive(Debug, PartialEq, Error)]
 pub enum Error {
-    #[error(display = "failed to parse integer: {:?}", _0)]
+    #[error("failed to parse integer: {0:?}")]
     InvalidInteger(prefix_int::Error),
-    #[error(display = "failed to parse string: {:?}", _0)]
+    #[error("failed to parse string: {0:?}")]
     InvalidString(prefix_string::Error),
-    #[error(display = "index is out of dynamic table bounds: {:?}", _0)]
+    #[error("index is out of dynamic table bounds: {0:?}")]
     InvalidIndex(vas::Error),
-    #[error(display = "dynamic table error: {}", _0)]
+    #[error("dynamic table error: {0}")]
     DynamicTableError(DynamicTableError),
-    #[error(display = "index '{}' is out of static table bounds", _0)]
+    #[error("index '{}' is out of static table bounds", _0)]
     InvalidStaticIndex(usize),
-    #[error(display = "invalid data prefix")]
+    #[error("invalid data prefix")]
     UnknownPrefix,
-    #[error(display = "missing references from dynamic table to decode header block")]
+    #[error("missing references from dynamic table to decode header block")]
     MissingRefs(usize),
-    #[error(display = "header prefix contains invalid base index: {:?}", _0)]
+    #[error("header prefix contains invalid base index: {0:?}")]
     BadBaseIndex(isize),
-    #[error(display = "data is unexpectedly truncated")]
+    #[error("data is unexpectedly truncated")]
     UnexpectedEnd,
 }
 
diff --git a/quinn-h3/src/qpack/dynamic.rs b/quinn-h3/src/qpack/dynamic.rs
index 5954550cf..df947345a 100644
--- a/quinn-h3/src/qpack/dynamic.rs
+++ b/quinn-h3/src/qpack/dynamic.rs
@@ -3,7 +3,7 @@ use std::{
     collections::{btree_map::Entry as BTEntry, hash_map::Entry, BTreeMap, HashMap, VecDeque},
 };
 
-use err_derive::Error;
+use thiserror::Error;
 
 use super::{field::HeaderField, static_::StaticTable};
 use crate::qpack::vas::{self, VirtualAddressSpace};
@@ -16,26 +16,23 @@ const SETTINGS_MAX_BLOCKED_STREAMS_MAX: usize = 65_535; // 2^16 - 1
 
 #[derive(Debug, PartialEq, Error)]
 pub enum Error {
-    #[error(display = "bad relative index: {}", _0)]
+    #[error("bad relative index: {0}")]
     BadRelativeIndex(usize),
-    #[error(display = "bad post base index: {}", _0)]
+    #[error("bad post base index: {0}")]
     BadPostbaseIndex(usize),
-    #[error(display = "decoded index out of bounds: {}", _0)]
+    #[error("decoded index out of bounds: {0}")]
     BadIndex(usize),
-    #[error(display = "tried to insert a field greater than dynamic table available size")]
+    #[error("tried to insert a field greater than dynamic table available size")]
     MaxTableSizeReached,
-    #[error(display = "table size setting is greater than maximum authorized")]
+    #[error("table size setting is greater than maximum authorized")]
     MaximumTableSizeTooLarge,
-    #[error(display = "max blocked stream setting is greater than maximum authorized")]
+    #[error("max blocked stream setting is greater than maximum authorized")]
     MaxBlockedStreamsTooLarge,
-    #[error(
-        display = "stream id '{}' is unknown or has already been acknowledged or canceled",
-        _0
-    )]
+    #[error("stream id '{0}' is unknown or has already been acknowledged or canceled")]
     UnknownStreamId(u64),
-    #[error(display = "tried to acknowledge encoder stream but no encoder data has been sent")]
+    #[error("tried to acknowledge encoder stream but no encoder data has been sent")]
     NoTrackingData,
-    #[error(display = "internal reference tracking error")]
+    #[error("internal reference tracking error")]
     InvalidTrackingCount,
 }
 
diff --git a/quinn-h3/src/qpack/encoder.rs b/quinn-h3/src/qpack/encoder.rs
index a6cfcac13..64179153c 100644
--- a/quinn-h3/src/qpack/encoder.rs
+++ b/quinn-h3/src/qpack/encoder.rs
@@ -2,7 +2,7 @@ use std::{cmp, io::Cursor};
 
 use bytes::{Buf, BufMut};
 
-use err_derive::Error;
+use thiserror::Error;
 
 use super::{
     block::{
@@ -26,13 +26,13 @@ use super::{
 
 #[derive(Debug, PartialEq, Error)]
 pub enum Error {
-    #[error(display = "failed to insert in dynamic table: {}", _0)]
+    #[error("failed to insert in dynamic table: {0}")]
     Insertion(DynamicTableError),
-    #[error(display = "prefixed string: {:?}", _0)]
+    #[error("prefixed string: {0:?}")]
     InvalidString(StringError),
-    #[error(display = "prefixed integer: {:?}", _0)]
+    #[error("prefixed integer: {0:?}")]
     InvalidInteger(IntError),
-    #[error(display = "invalid data prefix")]
+    #[error("invalid data prefix")]
     UnknownPrefix,
 }
 
diff --git a/quinn-proto/Cargo.toml b/quinn-proto/Cargo.toml
index 3483904c9..b63decf4f 100644
--- a/quinn-proto/Cargo.toml
+++ b/quinn-proto/Cargo.toml
@@ -34,6 +34,7 @@ ring = { version = "0.16.7", optional = true }
 rustls = { git = "https://github.com/ctz/rustls", rev = "fee894f7e030", features = ["quic"], optional = true }
 rustls-native-certs = { git = "https://github.com/kwantam/rustls-native-certs", rev = "52fc75ad4430", optional = true }
 slab = "0.4"
+thiserror = "1.0.21"
 tracing = "0.1.10"
 webpki = { version = "0.21", optional = true }
 
diff --git a/quinn-proto/src/coding.rs b/quinn-proto/src/coding.rs
index b923932e2..a9b8e67b6 100644
--- a/quinn-proto/src/coding.rs
+++ b/quinn-proto/src/coding.rs
@@ -1,12 +1,12 @@
 use std::net::{Ipv4Addr, Ipv6Addr};
 
 use bytes::{Buf, BufMut};
-use err_derive::Error;
+use thiserror::Error;
 
 use crate::VarInt;
 
 #[derive(Error, Debug, Copy, Clone, Eq, PartialEq)]
-#[error(display = "unexpected end of buffer")]
+#[error("unexpected end of buffer")]
 pub struct UnexpectedEnd;
 
 pub type Result<T> = ::std::result::Result<T, UnexpectedEnd>;
diff --git a/quinn-proto/src/config.rs b/quinn-proto/src/config.rs
index 62f0b5ff6..eb1bb6404 100644
--- a/quinn-proto/src/config.rs
+++ b/quinn-proto/src/config.rs
@@ -1,7 +1,7 @@
 use std::{convert::TryInto, fmt, num::TryFromIntError, sync::Arc, time::Duration};
 
-use err_derive::Error;
 use rand::RngCore;
+use thiserror::Error;
 
 #[cfg(feature = "rustls")]
 use crate::crypto::types::{Certificate, CertificateChain, PrivateKey};
@@ -626,7 +626,7 @@ where
 #[non_exhaustive]
 pub enum ConfigError {
     /// Value exceeds supported bounds
-    #[error(display = "value exceeds supported bounds")]
+    #[error("value exceeds supported bounds")]
     OutOfBounds,
 }
 
diff --git a/quinn-proto/src/connection/mod.rs b/quinn-proto/src/connection/mod.rs
index ebc076033..6669a2cb5 100644
--- a/quinn-proto/src/connection/mod.rs
+++ b/quinn-proto/src/connection/mod.rs
@@ -9,8 +9,8 @@ use std::{
 };
 
 use bytes::{Bytes, BytesMut};
-use err_derive::Error;
 use rand::{rngs::StdRng, Rng, SeedableRng};
+use thiserror::Error;
 use tracing::{debug, error, trace, trace_span, warn};
 
 use crate::{
@@ -26,7 +26,7 @@ use crate::{
         ConnectionEvent, ConnectionEventInner, ConnectionId, EcnCodepoint, EndpointEvent,
         EndpointEventInner, IssuedCid,
     },
-    transport_parameters::{self, TransportParameters},
+    transport_parameters::TransportParameters,
     Dir, Frame, Side, StreamId, Transmit, TransportError, TransportErrorCode, VarInt,
     LOC_CID_COUNT, MAX_STREAM_COUNT, MIN_INITIAL_SIZE, MIN_MTU, RESET_TOKEN_SIZE,
     TIMER_GRANULARITY, VERSION,
@@ -3010,25 +3010,25 @@ where
 #[derive(Debug, Error, Clone, PartialEq, Eq)]
 pub enum ConnectionError {
     /// The peer doesn't implement any supported version.
-    #[error(display = "peer doesn't implement any supported version")]
+    #[error("peer doesn't implement any supported version")]
     VersionMismatch,
     /// The peer violated the QUIC specification as understood by this implementation.
-    #[error(display = "{}", _0)]
-    TransportError(#[source] TransportError),
+    #[error("{0}")]
+    TransportError(#[from] TransportError),
     /// The peer's QUIC stack aborted the connection automatically.
-    #[error(display = "aborted by peer: {}", 0)]
+    #[error("aborted by peer: {}", 0)]
     ConnectionClosed(frame::ConnectionClose),
     /// The peer closed the connection.
-    #[error(display = "closed by peer: {}", 0)]
+    #[error("closed by peer: {}", 0)]
     ApplicationClosed(frame::ApplicationClose),
     /// The peer is unable to continue processing this connection, usually due to having restarted.
-    #[error(display = "reset by peer")]
+    #[error("reset by peer")]
     Reset,
     /// The peer has become unreachable.
-    #[error(display = "timed out")]
+    #[error("timed out")]
     TimedOut,
     /// The local application closed the connection.
-    #[error(display = "closed")]
+    #[error("closed")]
     LocallyClosed,
 }
 
@@ -3055,12 +3055,6 @@ impl From<ConnectionError> for io::Error {
     }
 }
 
-impl From<transport_parameters::Error> for ConnectionError {
-    fn from(e: transport_parameters::Error) -> Self {
-        TransportError::from(e).into()
-    }
-}
-
 #[derive(Clone)]
 enum State {
     Handshake(state::Handshake),
@@ -3223,16 +3217,16 @@ const MIN_PACKET_SPACE: usize = 40;
 #[derive(Debug, Error, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub enum SendDatagramError {
     /// The peer does not support receiving datagram frames
-    #[error(display = "datagrams not supported by peer")]
+    #[error("datagrams not supported by peer")]
     UnsupportedByPeer,
     /// Datagram support is disabled locally
-    #[error(display = "datagram support disabled")]
+    #[error("datagram support disabled")]
     Disabled,
     /// The datagram is larger than the connection can currently accommodate
     ///
     /// Indicates that the path MTU minus overhead or the limit advertised by the peer has been
     /// exceeded.
-    #[error(display = "datagram too large")]
+    #[error("datagram too large")]
     TooLarge,
 }
 
diff --git a/quinn-proto/src/connection/streams.rs b/quinn-proto/src/connection/streams.rs
index 481240591..9252cd55b 100644
--- a/quinn-proto/src/connection/streams.rs
+++ b/quinn-proto/src/connection/streams.rs
@@ -4,7 +4,7 @@ use std::{
 };
 
 use bytes::{BufMut, Bytes};
-use err_derive::Error;
+use thiserror::Error;
 use tracing::{debug, trace};
 
 use super::{
@@ -922,7 +922,7 @@ pub enum WriteError {
     /// be generated, indicating that retrying the write might succeed.
     ///
     /// [`StreamEvent::Writable`]: crate::StreamEvent::Writable
-    #[error(display = "unable to accept further writes")]
+    #[error("unable to accept further writes")]
     Blocked,
     /// The peer is no longer accepting data on this stream, and it has been implicitly reset. The
     /// stream cannot be finished or further written to.
@@ -930,13 +930,13 @@ pub enum WriteError {
     /// Carries an application-defined error code.
     ///
     /// [`StreamEvent::Finished`]: crate::StreamEvent::Finished
-    #[error(display = "stopped by peer: code {}", 0)]
+    #[error("stopped by peer: code {}", 0)]
     Stopped(VarInt),
     /// Unknown stream
     ///
     /// Occurs when attempting to access a stream after finishing it or observing that it has been
     /// stopped.
-    #[error(display = "unknown stream")]
+    #[error("unknown stream")]
     UnknownStream,
 }
 
@@ -1081,24 +1081,24 @@ pub enum ReadError {
     ///
     /// If more data on this stream is received from the peer, an `Event::StreamReadable` will be
     /// generated for this stream, indicating that retrying the read might succeed.
-    #[error(display = "blocked")]
+    #[error("blocked")]
     Blocked,
     /// The peer abandoned transmitting data on this stream.
     ///
     /// Carries an application-defined error code.
-    #[error(display = "reset by peer: code {}", 0)]
+    #[error("reset by peer: code {}", 0)]
     Reset(VarInt),
     /// Unknown stream
     ///
     /// Occurs when attempting to access a stream after stopping it, or observing that it has been
     /// finished or reset.
-    #[error(display = "unknown stream")]
+    #[error("unknown stream")]
     UnknownStream,
     /// Attempted an ordered read following an unordered read
     ///
     /// Performing an unordered read allows discontinuities to arise in the receive buffer of a
     /// stream which cannot be recovered, making further ordered reads impossible.
-    #[error(display = "ordered read after unordered read")]
+    #[error("ordered read after unordered read")]
     IllegalOrderedRead,
 }
 
@@ -1144,10 +1144,10 @@ pub enum FinishError {
     /// Carries an application-defined error code.
     ///
     /// [`StreamEvent::Finished`]: crate::StreamEvent::Finished
-    #[error(display = "stopped by peer: code {}", 0)]
+    #[error("stopped by peer: code {}", 0)]
     Stopped(VarInt),
     /// The stream has not yet been created or was already finished or stopped.
-    #[error(display = "unknown stream")]
+    #[error("unknown stream")]
     UnknownStream,
 }
 
diff --git a/quinn-proto/src/endpoint.rs b/quinn-proto/src/endpoint.rs
index 975ba1134..7e5bed061 100644
--- a/quinn-proto/src/endpoint.rs
+++ b/quinn-proto/src/endpoint.rs
@@ -9,9 +9,9 @@ use std::{
 };
 
 use bytes::{BufMut, Bytes, BytesMut};
-use err_derive::Error;
 use rand::{rngs::StdRng, Rng, RngCore, SeedableRng};
 use slab::Slab;
+use thiserror::Error;
 use tracing::{debug, trace, warn};
 
 use crate::{
@@ -807,18 +807,18 @@ pub enum ConnectError {
     /// The endpoint can no longer create new connections
     ///
     /// Indicates that a necessary component of the endpoint has been dropped or otherwise disabled.
-    #[error(display = "endpoint stopping")]
+    #[error("endpoint stopping")]
     EndpointStopping,
     /// The number of active connections on the local endpoint is at the limit
     ///
     /// Try using longer connection IDs.
-    #[error(display = "too many connections")]
+    #[error("too many connections")]
     TooManyConnections,
     /// The domain name supplied was malformed
-    #[error(display = "invalid DNS name: {}", _0)]
+    #[error("invalid DNS name: {0}")]
     InvalidDnsName(String),
     /// The transport configuration was invalid
-    #[error(display = "transport configuration error: {}", _0)]
+    #[error("transport configuration error: {0}")]
     Config(#[source] ConfigError),
 }
 
diff --git a/quinn-proto/src/packet.rs b/quinn-proto/src/packet.rs
index f80f597a1..56b13f0ee 100644
--- a/quinn-proto/src/packet.rs
+++ b/quinn-proto/src/packet.rs
@@ -1,7 +1,7 @@
 use std::{cmp::Ordering, io, ops::Range, str};
 
 use bytes::{Buf, BufMut, Bytes, BytesMut};
-use err_derive::Error;
+use thiserror::Error;
 
 use crate::{
     coding::{self, BufExt, BufMutExt},
@@ -711,13 +711,13 @@ pub(crate) enum LongType {
 
 #[derive(Debug, Error, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub(crate) enum PacketDecodeError {
-    #[error(display = "unsupported version {:x}", version)]
+    #[error("unsupported version {version:x}")]
     UnsupportedVersion {
         src_cid: ConnectionId,
         dst_cid: ConnectionId,
         version: u32,
     },
-    #[error(display = "invalid header: {}", _0)]
+    #[error("invalid header: {0}")]
     InvalidHeader(&'static str),
 }
 
diff --git a/quinn-proto/src/transport_parameters.rs b/quinn-proto/src/transport_parameters.rs
index ae0377d84..f8d3ba3a7 100644
--- a/quinn-proto/src/transport_parameters.rs
+++ b/quinn-proto/src/transport_parameters.rs
@@ -12,7 +12,7 @@ use std::{
 };
 
 use bytes::{buf::ext::BufExt as _, Buf, BufMut};
-use err_derive::Error;
+use thiserror::Error;
 
 use crate::{
     cid_generator::ConnectionIdGenerator,
@@ -246,10 +246,10 @@ impl PreferredAddress {
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Error)]
 pub enum Error {
     /// Parameters that are semantically invalid
-    #[error(display = "parameter had illegal value")]
+    #[error("parameter had illegal value")]
     IllegalValue,
     /// Catch-all error for problems while decoding transport parameters
-    #[error(display = "parameters were malformed")]
+    #[error("parameters were malformed")]
     Malformed,
 }
 
diff --git a/quinn-proto/src/varint.rs b/quinn-proto/src/varint.rs
index 3b7254cd5..7f57bc3cb 100644
--- a/quinn-proto/src/varint.rs
+++ b/quinn-proto/src/varint.rs
@@ -1,7 +1,7 @@
 use std::{convert::TryInto, fmt};
 
 use bytes::{Buf, BufMut};
-use err_derive::Error;
+use thiserror::Error;
 
 use crate::coding::{self, Codec, UnexpectedEnd};
 
@@ -141,7 +141,7 @@ impl Arbitrary for VarInt {
 
 /// Error returned when constructing a `VarInt` from a value >= 2^62
 #[derive(Debug, Copy, Clone, Eq, PartialEq, Error)]
-#[error(display = "value too large for varint encoding")]
+#[error("value too large for varint encoding")]
 pub struct VarIntBoundsExceeded;
 
 impl Codec for VarInt {
diff --git a/quinn/Cargo.toml b/quinn/Cargo.toml
index 610a5bac7..7cf7a1ac9 100644
--- a/quinn/Cargo.toml
+++ b/quinn/Cargo.toml
@@ -28,12 +28,12 @@ maintenance = { status = "experimental" }
 
 [dependencies]
 bytes = "0.5.2"
-err-derive = "0.2.3"
 futures = "0.3.1"
 libc = "0.2.69"
 mio = "0.6"
 proto = { package = "quinn-proto", path = "../quinn-proto", version = "0.6.1" }
 rustls = { git = "https://github.com/ctz/rustls", rev = "fee894f7e030", features = ["quic"], optional = true }
+thiserror = "1.0.21"
 tracing = "0.1.10"
 tokio = { version = "0.2.6", features = ["rt-core", "io-driver", "time"] }
 webpki = { version = "0.21", optional = true }
diff --git a/quinn/src/builders.rs b/quinn/src/builders.rs
index 19d491f19..dd1bf5615 100644
--- a/quinn/src/builders.rs
+++ b/quinn/src/builders.rs
@@ -1,7 +1,7 @@
-use std::{io, net::SocketAddr, str, sync::Arc};
+use std::{io, net::SocketAddr, sync::Arc};
 
-use err_derive::Error;
 use proto::generic::{ClientConfig, EndpointConfig, ServerConfig};
+use thiserror::Error;
 use tracing::error;
 
 use crate::{
@@ -119,7 +119,7 @@ where
 #[derive(Debug, Error)]
 pub enum EndpointError {
     /// An error during setup of the underlying UDP socket.
-    #[error(display = "failed to set up UDP socket: {}", _0)]
+    #[error("failed to set up UDP socket: {0}")]
     Socket(io::Error),
 }
 
diff --git a/quinn/src/connection.rs b/quinn/src/connection.rs
index 150285210..5e9c4d03c 100644
--- a/quinn/src/connection.rs
+++ b/quinn/src/connection.rs
@@ -11,12 +11,12 @@ use std::{
 };
 
 use bytes::Bytes;
-use err_derive::Error;
 use futures::{
     channel::{mpsc, oneshot},
     FutureExt, StreamExt,
 };
 use proto::{ConnectionError, ConnectionHandle, Dir, StreamEvent, StreamId};
+use thiserror::Error;
 use tokio::time::{delay_until, Delay, Instant as TokioInstant};
 use tracing::info_span;
 
@@ -984,18 +984,18 @@ where
 #[derive(Debug, Error, Clone, Eq, PartialEq)]
 pub enum SendDatagramError {
     /// The peer does not support receiving datagram frames
-    #[error(display = "datagrams not supported by peer")]
+    #[error("datagrams not supported by peer")]
     UnsupportedByPeer,
     /// Datagram support is disabled locally
-    #[error(display = "datagram support disabled")]
+    #[error("datagram support disabled")]
     Disabled,
     /// The datagram is larger than the connection can currently accommodate
     ///
     /// Indicates that the path MTU minus overhead or the limit advertised by the peer has been
     /// exceeded.
-    #[error(display = "datagram too large")]
+    #[error("datagram too large")]
     TooLarge,
     /// The connection was closed
-    #[error(display = "connection closed: {}", _0)]
+    #[error("connection closed: {0}")]
     ConnectionClosed(ConnectionError),
 }
diff --git a/quinn/src/streams.rs b/quinn/src/streams.rs
index c2d6204cb..870e0b3ed 100644
--- a/quinn/src/streams.rs
+++ b/quinn/src/streams.rs
@@ -3,18 +3,17 @@ use std::{
     io,
     mem::MaybeUninit,
     pin::Pin,
-    str,
     task::{Context, Poll},
 };
 
 use bytes::Bytes;
-use err_derive::Error;
 use futures::{
     channel::oneshot,
     io::{AsyncRead, AsyncWrite},
     ready, FutureExt,
 };
 use proto::{ConnectionError, FinishError, StreamId};
+use thiserror::Error;
 
 use crate::{connection::ConnectionRef, VarInt};
 
@@ -536,19 +535,13 @@ where
 #[derive(Debug, Error, Clone, PartialEq, Eq)]
 pub enum ReadToEndError {
     /// An error occurred during reading
-    #[error(display = "read error: {}", 0)]
-    Read(ReadError),
+    #[error("read error: {0}")]
+    Read(#[from] ReadError),
     /// The stream is larger than the user-supplied limit
-    #[error(display = "stream too long")]
+    #[error("stream too long")]
     TooLong,
 }
 
-impl From<ReadError> for ReadToEndError {
-    fn from(x: ReadError) -> Self {
-        ReadToEndError::Read(x)
-    }
-}
-
 impl<S> AsyncRead for RecvStream<S>
 where
     S: proto::crypto::Session,
@@ -607,19 +600,19 @@ pub enum ReadError {
     /// The peer abandoned transmitting data on this stream.
     ///
     /// Carries an application-defined error code.
-    #[error(display = "stream reset by peer: error {}", 0)]
+    #[error("stream reset by peer: error {0}")]
     Reset(VarInt),
     /// The connection was closed.
-    #[error(display = "connection closed: {}", _0)]
+    #[error("connection closed: {0}")]
     ConnectionClosed(ConnectionError),
     /// Unknown stream
-    #[error(display = "unknown stream")]
+    #[error("unknown stream")]
     UnknownStream,
     /// Attempted an ordered read following an unordered read
     ///
     /// Performing an unordered read allows discontinuities to arise in the receive buffer of a
     /// stream which cannot be recovered, making further ordered reads impossible.
-    #[error(display = "ordered read after unordered read")]
+    #[error("ordered read after unordered read")]
     IllegalOrderedRead,
     /// This was a 0-RTT stream and the server rejected it.
     ///
@@ -627,7 +620,7 @@ pub enum ReadError {
     /// [`Connecting::into_0rtt()`].
     ///
     /// [`Connecting::into_0rtt()`]: crate::generic::Connecting::into_0rtt()
-    #[error(display = "0-RTT rejected")]
+    #[error("0-RTT rejected")]
     ZeroRttRejected,
 }
 
@@ -652,13 +645,13 @@ pub enum WriteError {
     /// The peer is no longer accepting data on this stream.
     ///
     /// Carries an application-defined error code.
-    #[error(display = "sending stopped by peer: error {}", 0)]
+    #[error("sending stopped by peer: error {0}")]
     Stopped(VarInt),
     /// The connection was closed.
-    #[error(display = "connection closed: {}", _0)]
+    #[error("connection closed: {0}")]
     ConnectionClosed(ConnectionError),
     /// Unknown stream
-    #[error(display = "unknown stream")]
+    #[error("unknown stream")]
     UnknownStream,
     /// This was a 0-RTT stream and the server rejected it.
     ///
@@ -666,7 +659,7 @@ pub enum WriteError {
     /// [`Connecting::into_0rtt()`].
     ///
     /// [`Connecting::into_0rtt()`]: crate::generic::Connecting::into_0rtt()
-    #[error(display = "0-RTT rejected")]
+    #[error("0-RTT rejected")]
     ZeroRttRejected,
 }
 
@@ -674,10 +667,10 @@ pub enum WriteError {
 #[derive(Debug, Error, Clone, PartialEq, Eq)]
 pub enum StoppedError {
     /// The connection was closed.
-    #[error(display = "connection closed: {}", _0)]
+    #[error("connection closed: {0}")]
     ConnectionClosed(ConnectionError),
     /// Unknown stream
-    #[error(display = "unknown stream")]
+    #[error("unknown stream")]
     UnknownStream,
     /// This was a 0-RTT stream and the server rejected it.
     ///
@@ -685,7 +678,7 @@ pub enum StoppedError {
     /// [`Connecting::into_0rtt()`].
     ///
     /// [`Connecting::into_0rtt()`]: crate::generic::Connecting::into_0rtt()
-    #[error(display = "0-RTT rejected")]
+    #[error("0-RTT rejected")]
     ZeroRttRejected,
 }
 
@@ -760,10 +753,10 @@ where
 #[derive(Debug, Error, Clone, PartialEq, Eq)]
 pub enum ReadExactError {
     /// The stream finished before all bytes were read
-    #[error(display = "stream finished early")]
+    #[error("stream finished early")]
     FinishedEarly,
     /// A read error occurred
-    #[error(display = "{}", 0)]
+    #[error("{0}")]
     ReadError(ReadError),
 }