diff --git a/ethcore/src/types/executed.rs b/ethcore/src/types/executed.rs
index f03a1c26b..fc0f864ed 100644
--- a/ethcore/src/types/executed.rs
+++ b/ethcore/src/types/executed.rs
@@ -21,6 +21,7 @@ use util::Bytes;
 use trace::Trace;
 use types::log_entry::LogEntry;
 use ipc::binary::BinaryConvertError;
+use std::fmt;
 use std::mem;
 use std::collections::VecDeque;
 
@@ -104,6 +105,39 @@ pub enum ExecutionError {
 	TransactionMalformed(String),
 }
 
+impl fmt::Display for ExecutionError {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		use self::ExecutionError::*;
+
+		let msg = match *self {
+			NotEnoughBaseGas { required, got } => {
+				format!("Not enough base gas. {} is required, but only {} paid",
+					required, got)
+			}
+			BlockGasLimitReached { gas_limit, gas_used, gas } => {
+				format!("Block gas limit reached. The limit is {}, {} has \
+					already been used, and {} more is required",
+					gas_limit, gas_used, gas)
+			}
+			InvalidNonce { expected, got } => {
+				format!("Invalid transaction nonce: expected {}, found {}",
+					expected, got)
+			}
+			NotEnoughCash { required, got } => {
+				format!("Cost of transaction exceeds sender balance. {} is required \
+					but the sender only has {}", required, got)
+			}
+			Internal => {
+				"Internal evm error".into()
+			}
+			TransactionMalformed(ref err) => {
+				format!("Malformed transaction: {}", err)
+			}
+		};
+
+		f.write_fmt(format_args!("Transaction execution error ({}).", msg))
+	}
+}
 
 /// Transaction execution result.
 pub type ExecutionResult = Result<Executed, ExecutionError>;
diff --git a/util/src/crypto.rs b/util/src/crypto.rs
index 040db3bca..3eff70717 100644
--- a/util/src/crypto.rs
+++ b/util/src/crypto.rs
@@ -21,6 +21,7 @@ use bytes::*;
 use secp256k1::{key, Secp256k1};
 use rand::os::OsRng;
 use sha3::Hashable;
+use std::fmt;
 
 /// Secret key for secp256k1 EC operations. 256 bit generic "hash" data.
 pub type Secret = H256;
@@ -69,6 +70,20 @@ pub enum CryptoError {
 	Io(::std::io::Error),
 }
 
+impl fmt::Display for CryptoError {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		let msg = match *self {
+			CryptoError::InvalidSecret => "Invalid secret key".into(),
+			CryptoError::InvalidPublic => "Invalid public key".into(),
+			CryptoError::InvalidSignature => "Invalid EC signature".into(),
+			CryptoError::InvalidMessage => "Invalid AES message".into(),
+			CryptoError::Io(ref err) => format!("I/O error: {}", err),
+		};
+
+		f.write_fmt(format_args!("Crypto error ({})", msg))
+	}
+}
+
 impl From<::secp256k1::Error> for CryptoError {
 	fn from(e: ::secp256k1::Error) -> CryptoError {
 		match e {
diff --git a/util/src/io/mod.rs b/util/src/io/mod.rs
index 40cdbc368..93805a46a 100644
--- a/util/src/io/mod.rs
+++ b/util/src/io/mod.rs
@@ -56,6 +56,7 @@ mod service;
 mod worker;
 
 use mio::{EventLoop, Token};
+use std::fmt;
 
 #[derive(Debug)]
 /// IO Error
@@ -64,6 +65,16 @@ pub enum IoError {
 	Mio(::std::io::Error),
 }
 
+impl fmt::Display for IoError {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		// just defer to the std implementation for now.
+		// we can refine the formatting when more variants are added.
+		match *self {
+			IoError::Mio(ref std_err) => std_err.fmt(f)
+		}
+	}
+}
+
 impl<Message> From<::mio::NotifyError<service::IoMessage<Message>>> for IoError where Message: Send + Clone {
 	fn from(_err: ::mio::NotifyError<service::IoMessage<Message>>) -> IoError {
 		IoError::Mio(::std::io::Error::new(::std::io::ErrorKind::ConnectionAborted, "Network IO notification error"))
diff --git a/util/src/network/error.rs b/util/src/network/error.rs
index 31e1d785b..e4705fc9e 100644
--- a/util/src/network/error.rs
+++ b/util/src/network/error.rs
@@ -17,6 +17,7 @@
 use io::IoError;
 use crypto::CryptoError;
 use rlp::*;
+use std::fmt;
 
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 pub enum DisconnectReason
@@ -56,6 +57,30 @@ impl DisconnectReason {
 	}
 }
 
+impl fmt::Display for DisconnectReason {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		use self::DisconnectReason::*;
+
+		let msg = match *self {
+			DisconnectRequested => "disconnect requested",
+			TCPError => "TCP error",
+			BadProtocol => "bad protocol",
+			UselessPeer => "useless peer",
+			TooManyPeers => "too many peers",
+			DuplicatePeer => "duplicate peer",
+			IncompatibleProtocol => "incompatible protocol",
+			NullIdentity => "null identity",
+			ClientQuit => "client quit",
+			UnexpectedIdentity => "unexpected identity",
+			LocalIdentity => "local identity",
+			PingTimeout => "ping timeout",
+			Unknown => "unknown",
+		};
+
+		f.write_str(msg)
+	}
+}
+
 #[derive(Debug)]
 /// Network error.
 pub enum NetworkError {
@@ -73,6 +98,23 @@ pub enum NetworkError {
 	Io(IoError),
 }
 
+impl fmt::Display for NetworkError {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		use self::NetworkError::*;
+
+		let msg = match *self {
+			Auth => "Authentication failure".into(),
+			BadProtocol => "Bad protocol".into(),
+			Expired => "Expired message".into(),
+			PeerNotFound => "Peer not found".into(),
+			Disconnect(ref reason) => format!("Peer disconnected: {}", reason),
+			Io(ref err) => format!("Socket I/O error: {}", err),
+		};
+
+		f.write_fmt(format_args!("Network error ({})", msg))
+	}
+}
+
 impl From<DecoderError> for NetworkError {
 	fn from(_err: DecoderError) -> NetworkError {
 		NetworkError::Auth