diff --git a/conn.go b/conn.go
index ed6a3a09..e92344f1 100644
--- a/conn.go
+++ b/conn.go
@@ -420,7 +420,7 @@ func (c *Conn) IsClosed() bool {
 	return c.pgConn.IsClosed()
 }
 
-func (c *Conn) die(err error) {
+func (c *Conn) die() {
 	if c.IsClosed() {
 		return
 	}
@@ -588,14 +588,6 @@ func (c *Conn) execPrepared(ctx context.Context, sd *pgconn.StatementDescription
 	return result.CommandTag, result.Err
 }
 
-type unknownArgumentTypeQueryExecModeExecError struct {
-	arg any
-}
-
-func (e *unknownArgumentTypeQueryExecModeExecError) Error() string {
-	return fmt.Sprintf("cannot use unregistered type %T as query argument in QueryExecModeExec", e.arg)
-}
-
 func (c *Conn) execSQLParams(ctx context.Context, sql string, args []any) (pgconn.CommandTag, error) {
 	err := c.eqb.Build(c.typeMap, nil, args)
 	if err != nil {
diff --git a/tx.go b/tx.go
index 168d7ba6..571e5e00 100644
--- a/tx.go
+++ b/tx.go
@@ -3,7 +3,6 @@ package pgx
 import (
 	"context"
 	"errors"
-	"fmt"
 	"strconv"
 	"strings"
 
@@ -103,7 +102,7 @@ func (c *Conn) BeginTx(ctx context.Context, txOptions TxOptions) (Tx, error) {
 	if err != nil {
 		// begin should never fail unless there is an underlying connection issue or
 		// a context timeout. In either case, the connection is possibly broken.
-		c.die(errors.New("failed to begin transaction"))
+		c.die()
 		return nil, err
 	}
 
@@ -216,7 +215,7 @@ func (tx *dbTx) Rollback(ctx context.Context) error {
 	tx.closed = true
 	if err != nil {
 		// A rollback failure leaves the connection in an undefined state
-		tx.conn.die(fmt.Errorf("rollback failed: %w", err))
+		tx.conn.die()
 		return err
 	}