diff --git a/examples/Cargo.toml b/examples/Cargo.toml
index 3670ba90..534e5c9d 100644
--- a/examples/Cargo.toml
+++ b/examples/Cargo.toml
@@ -1,12 +1,11 @@
 [package]
 name = "rustls-examples"
 version = "0.0.1"
-edition = "2018"
+edition = "2021"
 authors = ["Joseph Birr-Pixton <jpixton@gmail.com>"]
 license = "Apache-2.0/ISC/MIT"
 description = "Rustls example code and tests."
 publish = false
-resolver = "2"
 
 [features]
 default = ["logging"]
diff --git a/examples/src/bin/limitedclient.rs b/examples/src/bin/limitedclient.rs
index 9cd07849..735026e2 100644
--- a/examples/src/bin/limitedclient.rs
+++ b/examples/src/bin/limitedclient.rs
@@ -3,7 +3,6 @@
 /// observe using `nm` that the binary of this program does not contain any AES code.
 use std::sync::Arc;
 
-use std::convert::TryInto;
 use std::io::{stdout, Read, Write};
 use std::net::TcpStream;
 
diff --git a/examples/src/bin/simple_0rtt_client.rs b/examples/src/bin/simple_0rtt_client.rs
index 85f8a952..0480f903 100644
--- a/examples/src/bin/simple_0rtt_client.rs
+++ b/examples/src/bin/simple_0rtt_client.rs
@@ -1,6 +1,5 @@
 use std::sync::Arc;
 
-use std::convert::TryInto;
 use std::io::{stdout, Read, Write};
 use std::net::TcpStream;
 
diff --git a/examples/src/bin/simpleclient.rs b/examples/src/bin/simpleclient.rs
index 5d017833..a16eaa34 100644
--- a/examples/src/bin/simpleclient.rs
+++ b/examples/src/bin/simpleclient.rs
@@ -9,7 +9,6 @@
 /// that is sensible outside of example code.
 use std::sync::Arc;
 
-use std::convert::TryInto;
 use std::io::{stdout, Read, Write};
 use std::net::TcpStream;
 
diff --git a/examples/src/bin/tlsclient-mio.rs b/examples/src/bin/tlsclient-mio.rs
index 1e85cb0a..503941c9 100644
--- a/examples/src/bin/tlsclient-mio.rs
+++ b/examples/src/bin/tlsclient-mio.rs
@@ -4,7 +4,6 @@ use std::sync::{Arc, Mutex};
 use mio::net::TcpStream;
 
 use std::collections;
-use std::convert::TryInto;
 use std::fs;
 use std::io;
 use std::io::{BufReader, Read, Write};
diff --git a/fuzz/Cargo.toml b/fuzz/Cargo.toml
index 9d74cbd4..0fa05d4c 100644
--- a/fuzz/Cargo.toml
+++ b/fuzz/Cargo.toml
@@ -4,7 +4,7 @@ name = "rustls-fuzz"
 version = "0.0.1"
 authors = ["Automatically generated"]
 publish = false
-resolver = "2"
+edition = "2021"
 
 [package.metadata]
 cargo-fuzz = true
diff --git a/fuzz/fuzzers/client.rs b/fuzz/fuzzers/client.rs
index 5c24a331..460eb6cd 100644
--- a/fuzz/fuzzers/client.rs
+++ b/fuzz/fuzzers/client.rs
@@ -9,7 +9,6 @@ use rustls::{
     ClientConnection,
     RootCertStore
 };
-use std::convert::TryInto;
 use std::io;
 use std::sync::Arc;
 
diff --git a/fuzz/fuzzers/deframer.rs b/fuzz/fuzzers/deframer.rs
index cfa0be0e..354bb931 100644
--- a/fuzz/fuzzers/deframer.rs
+++ b/fuzz/fuzzers/deframer.rs
@@ -5,7 +5,6 @@ extern crate rustls;
 
 use rustls::internal::msgs::deframer;
 use rustls::internal::msgs::message::Message;
-use std::convert::TryFrom;
 use std::io;
 
 fuzz_target!(|data: &[u8]| {
diff --git a/fuzz/fuzzers/fragment.rs b/fuzz/fuzzers/fragment.rs
index 965798ef..e7d9f7bf 100644
--- a/fuzz/fuzzers/fragment.rs
+++ b/fuzz/fuzzers/fragment.rs
@@ -7,7 +7,6 @@ use rustls::internal::msgs::base::Payload;
 use rustls::internal::msgs::codec::Reader;
 use rustls::internal::msgs::fragmenter::MessageFragmenter;
 use rustls::internal::msgs::message::{Message, OpaqueMessage, PlainMessage};
-use std::convert::TryFrom;
 
 fuzz_target!(|data: &[u8]| {
     let mut rdr = Reader::init(data);
diff --git a/fuzz/fuzzers/hsjoiner.rs b/fuzz/fuzzers/hsjoiner.rs
index f7a1f24f..e9f65dd9 100644
--- a/fuzz/fuzzers/hsjoiner.rs
+++ b/fuzz/fuzzers/hsjoiner.rs
@@ -2,7 +2,6 @@
 #[macro_use] extern crate libfuzzer_sys;
 extern crate rustls;
 
-use std::convert::TryFrom;
 use rustls::internal::msgs::codec::Reader;
 use rustls::internal::msgs::hsjoiner;
 use rustls::internal::msgs::message;
diff --git a/fuzz/fuzzers/message.rs b/fuzz/fuzzers/message.rs
index 1d28e25f..00b2abc5 100644
--- a/fuzz/fuzzers/message.rs
+++ b/fuzz/fuzzers/message.rs
@@ -5,7 +5,6 @@ extern crate rustls;
 
 use rustls::internal::msgs::codec::Reader;
 use rustls::internal::msgs::message::{Message, PlainMessage, OpaqueMessage};
-use std::convert::TryFrom;
 
 fuzz_target!(|data: &[u8]| {
     let mut rdr = Reader::init(data);
diff --git a/rustls/Cargo.toml b/rustls/Cargo.toml
index 9ca97dd8..7a1ee78d 100644
--- a/rustls/Cargo.toml
+++ b/rustls/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "rustls"
 version = "0.20.8"
-edition = "2018"
+edition = "2021"
 rust-version = "1.57"
 license = "Apache-2.0/ISC/MIT"
 readme = "../README.md"
@@ -11,7 +11,6 @@ repository = "https://github.com/rustls/rustls"
 categories = ["network-programming", "cryptography"]
 autobenches = false
 build = "build.rs"
-resolver = "2"
 
 [build-dependencies]
 rustversion = { version = "1.0.6", optional = true }
diff --git a/rustls/examples/internal/bench.rs b/rustls/examples/internal/bench.rs
index 5ef69d05..97049e75 100644
--- a/rustls/examples/internal/bench.rs
+++ b/rustls/examples/internal/bench.rs
@@ -3,7 +3,6 @@
 // Note: we don't use any of the standard 'cargo bench', 'test::Bencher',
 // etc. because it's unstable at the time of writing.
 
-use std::convert::TryInto;
 use std::env;
 use std::fs;
 use std::io::{self, Read, Write};
diff --git a/rustls/examples/internal/bogo_shim.rs b/rustls/examples/internal/bogo_shim.rs
index b49b07e4..4cbbe047 100644
--- a/rustls/examples/internal/bogo_shim.rs
+++ b/rustls/examples/internal/bogo_shim.rs
@@ -15,7 +15,6 @@ use rustls::server::ClientHello;
 use rustls::{CipherSuite, ProtocolVersion};
 use rustls::{ClientConnection, Connection, ServerConnection};
 
-use std::convert::TryInto;
 use std::env;
 use std::fs;
 use std::io;
diff --git a/rustls/examples/internal/trytls_shim.rs b/rustls/examples/internal/trytls_shim.rs
index f47bbd02..5bed489f 100644
--- a/rustls/examples/internal/trytls_shim.rs
+++ b/rustls/examples/internal/trytls_shim.rs
@@ -5,7 +5,6 @@
 //
 
 use rustls::{ClientConfig, ClientConnection, Error, OwnedTrustAnchor, RootCertStore};
-use std::convert::TryInto;
 use std::env;
 use std::error::Error as StdError;
 use std::fs::File;
diff --git a/rustls/src/client/client_conn.rs b/rustls/src/client/client_conn.rs
index 38131fd3..42da72b1 100644
--- a/rustls/src/client/client_conn.rs
+++ b/rustls/src/client/client_conn.rs
@@ -20,7 +20,6 @@ use super::hs;
 #[cfg(feature = "quic")]
 use crate::quic;
 
-use std::convert::TryFrom;
 use std::error::Error as StdError;
 use std::marker::PhantomData;
 use std::net::IpAddr;
@@ -216,7 +215,6 @@ impl ClientConfig {
 /// so you can do:
 ///
 /// ```
-/// # use std::convert::{TryInto, TryFrom};
 /// # use rustls::ServerName;
 /// ServerName::try_from("example.com").expect("invalid DNS name");
 ///
diff --git a/rustls/src/conn.rs b/rustls/src/conn.rs
index f7d93a8c..861caccf 100644
--- a/rustls/src/conn.rs
+++ b/rustls/src/conn.rs
@@ -26,7 +26,6 @@ use crate::vecbuf::ChunkVecBuffer;
 #[cfg(feature = "quic")]
 use std::collections::VecDeque;
 
-use std::convert::TryFrom;
 use std::fmt::Debug;
 use std::io;
 use std::mem;
diff --git a/rustls/src/lib.rs b/rustls/src/lib.rs
index 9ad18489..c3d9f3b8 100644
--- a/rustls/src/lib.rs
+++ b/rustls/src/lib.rs
@@ -133,7 +133,6 @@
 //! # use rustls;
 //! # use webpki;
 //! # use std::sync::Arc;
-//! # use std::convert::TryInto;
 //! # let mut root_store = rustls::RootCertStore::empty();
 //! # root_store.add_server_trust_anchors(
 //! #  webpki_roots::TLS_SERVER_ROOTS
diff --git a/rustls/src/msgs/codec.rs b/rustls/src/msgs/codec.rs
index 9ad1b128..70802b5e 100644
--- a/rustls/src/msgs/codec.rs
+++ b/rustls/src/msgs/codec.rs
@@ -1,4 +1,3 @@
-use std::convert::TryInto;
 use std::fmt::Debug;
 
 /// Wrapper over a slice of bytes that allows reading chunks from
diff --git a/rustls/src/msgs/deframer.rs b/rustls/src/msgs/deframer.rs
index 2ada2d81..8a9e4822 100644
--- a/rustls/src/msgs/deframer.rs
+++ b/rustls/src/msgs/deframer.rs
@@ -126,7 +126,6 @@ mod tests {
     use super::MessageDeframer;
     use crate::msgs::message::{Message, OpaqueMessage};
     use crate::{msgs, Error};
-    use std::convert::TryFrom;
     use std::io;
 
     const FIRST_MESSAGE: &[u8] = include_bytes!("../testdata/deframer-test.1.bin");
diff --git a/rustls/src/msgs/message.rs b/rustls/src/msgs/message.rs
index a8b8308f..6d1b2e60 100644
--- a/rustls/src/msgs/message.rs
+++ b/rustls/src/msgs/message.rs
@@ -7,8 +7,6 @@ use crate::msgs::codec::{Codec, Reader};
 use crate::msgs::enums::{AlertDescription, AlertLevel, ContentType, HandshakeType};
 use crate::msgs::handshake::HandshakeMessagePayload;
 
-use std::convert::TryFrom;
-
 #[derive(Debug)]
 pub enum MessagePayload {
     Alert(AlertMessagePayload),
diff --git a/rustls/src/msgs/message_test.rs b/rustls/src/msgs/message_test.rs
index a50df90a..ce0b6885 100644
--- a/rustls/src/msgs/message_test.rs
+++ b/rustls/src/msgs/message_test.rs
@@ -5,7 +5,6 @@ use super::codec::Reader;
 use super::enums::{AlertDescription, AlertLevel, HandshakeType};
 use super::message::{Message, OpaqueMessage, PlainMessage};
 
-use std::convert::TryFrom;
 use std::fs;
 use std::io::Read;
 use std::path::{Path, PathBuf};
diff --git a/rustls/src/msgs/mod.rs b/rustls/src/msgs/mod.rs
index 655ff13a..2651f901 100644
--- a/rustls/src/msgs/mod.rs
+++ b/rustls/src/msgs/mod.rs
@@ -30,8 +30,6 @@ mod message_test;
 
 #[cfg(test)]
 mod test {
-    use std::convert::TryFrom;
-
     #[test]
     fn smoketest() {
         use super::codec::Reader;
diff --git a/rustls/src/msgs/persist_test.rs b/rustls/src/msgs/persist_test.rs
index c4a4165d..996da015 100644
--- a/rustls/src/msgs/persist_test.rs
+++ b/rustls/src/msgs/persist_test.rs
@@ -6,8 +6,6 @@ use crate::key::Certificate;
 use crate::ticketer::TimeBase;
 use crate::tls13::TLS13_AES_128_GCM_SHA256;
 
-use std::convert::TryInto;
-
 #[test]
 fn clientsessionkey_is_debug() {
     let name = "hello".try_into().unwrap();
diff --git a/rustls/src/sign.rs b/rustls/src/sign.rs
index 9c916f69..649466cc 100644
--- a/rustls/src/sign.rs
+++ b/rustls/src/sign.rs
@@ -7,7 +7,6 @@ use crate::x509::{wrap_in_asn1_len, wrap_in_sequence};
 use ring::io::der;
 use ring::signature::{self, EcdsaKeyPair, Ed25519KeyPair, RsaKeyPair};
 
-use std::convert::TryFrom;
 use std::error::Error as StdError;
 use std::fmt;
 use std::sync::Arc;
diff --git a/rustls/src/verify.rs b/rustls/src/verify.rs
index 58fd7dc6..d81b96ec 100644
--- a/rustls/src/verify.rs
+++ b/rustls/src/verify.rs
@@ -11,7 +11,6 @@ use crate::msgs::handshake::{DigitallySignedStruct, DistinguishedNames};
 
 use ring::digest::Digest;
 
-use std::convert::TryFrom;
 use std::sync::Arc;
 use std::time::SystemTime;
 
diff --git a/rustls/src/verifybench.rs b/rustls/src/verifybench.rs
index 9ddb2711..a1099f85 100644
--- a/rustls/src/verifybench.rs
+++ b/rustls/src/verifybench.rs
@@ -4,7 +4,6 @@
 // Note: we don't use any of the standard 'cargo bench', 'test::Bencher',
 // etc. because it's unstable at the time of writing.
 
-use std::convert::TryInto;
 use std::time::{Duration, Instant, SystemTime};
 
 use crate::key;
diff --git a/rustls/tests/api.rs b/rustls/tests/api.rs
index 5f47cc90..a14dd8f6 100644
--- a/rustls/tests/api.rs
+++ b/rustls/tests/api.rs
@@ -1,8 +1,5 @@
 //! Assorted public API tests.
 use std::cell::RefCell;
-use std::convert::TryFrom;
-#[cfg(feature = "tls12")]
-use std::convert::TryInto;
 use std::fmt;
 use std::io::{self, IoSlice, Read, Write};
 use std::mem;
diff --git a/rustls/tests/common/mod.rs b/rustls/tests/common/mod.rs
index d176ed87..63e6ba8a 100644
--- a/rustls/tests/common/mod.rs
+++ b/rustls/tests/common/mod.rs
@@ -1,6 +1,5 @@
 #![allow(dead_code)]
 
-use std::convert::{TryFrom, TryInto};
 use std::io;
 use std::ops::{Deref, DerefMut};
 use std::sync::Arc;