diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6df5a998..dfd9aaf8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -9,6 +9,7 @@ jobs:
   build_and_test:
     name: Build and test
     runs-on: ubuntu-latest
+    continue-on-error: ${{ matrix.toolchain != 'stable' }}
     strategy:
       matrix:
         toolchain: [stable, beta]
diff --git a/src/pbft/mod.rs b/src/pbft/mod.rs
index b2bf91e6..d0e5d737 100644
--- a/src/pbft/mod.rs
+++ b/src/pbft/mod.rs
@@ -575,10 +575,7 @@ impl<M: ReplicaCommon> OnEvent<ProgressPrepared> for Replica<M::PN, M::DN, M::CW
         &mut self,
         ProgressPrepared(op_num): ProgressPrepared,
         _: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         warn!("progress prepared {op_num}");
         let entry = &self.log[op_num as usize];
         let pre_prepare = entry
@@ -1032,10 +1029,8 @@ impl<M: ReplicaCommon> OnEvent<StateTransfer> for Replica<M::PN, M::DN, M::CW, M
         &mut self,
         StateTransfer(op_num): StateTransfer,
         _: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
+        // TODO
         anyhow::bail!("{:?} timeout", StateTransfer(op_num))
     }
 }
@@ -1045,10 +1040,7 @@ impl<M: ReplicaCommon> OnEvent<Recv<QueryNewView>> for Replica<M::PN, M::DN, M::
         &mut self,
         Recv(query_new_view): Recv<QueryNewView>,
         _: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         if let Some(new_view) = self.new_views.get(&query_new_view.view_num) {
             self.net.send(query_new_view.replica_id, new_view.clone())?
         }
@@ -1064,10 +1056,7 @@ impl<M: ReplicaCommon> OnEvent<DoViewChange> for Replica<M::PN, M::DN, M::CW, M:
         &mut self,
         DoViewChange(view_num): DoViewChange,
         timer: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         warn!("[{}] do view change for view {view_num}", self.id);
         assert!(view_num >= self.view_num);
         self.view_num = view_num;
@@ -1085,10 +1074,7 @@ impl<M: ReplicaCommon> OnEvent<ProgressViewChange> for Replica<M::PN, M::DN, M::
         &mut self,
         ProgressViewChange: ProgressViewChange,
         _: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         self.do_view_change()
     }
 }
@@ -1122,10 +1108,7 @@ impl<M: ReplicaCommon> OnEvent<Signed<ViewChange>> for Replica<M::PN, M::DN, M::
         &mut self,
         Signed(view_change): Signed<ViewChange>,
         timer: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         if view_change.view_num == self.view_num {
             self.net.send(All, view_change.clone())?;
             self.insert_view_change(view_change, timer)?
@@ -1159,10 +1142,7 @@ impl<M: ReplicaCommon> OnEvent<Recv<Verifiable<ViewChange>>>
         &mut self,
         Recv(view_change): Recv<Verifiable<ViewChange>>,
         _: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         if view_change.view_num < self.view_num {
             return Ok(());
         }
@@ -1185,10 +1165,7 @@ impl<M: ReplicaCommon> OnEvent<Verified<ViewChange>>
         &mut self,
         Verified(view_change): Verified<ViewChange>,
         timer: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         self.insert_view_change(view_change, timer)
     }
 }
@@ -1236,15 +1213,19 @@ fn pre_prepares_for_view_changes(
     Ok(pre_prepares)
 }
 
+impl<M: ReplicaCommon> Replica<M::PN, M::DN, M::CW, M::S, M::A, M> {
+    fn have_entered(&self, view_num: u32) -> bool {
+        self.view_num > view_num || self.view_num == view_num && !self.view_change()
+    }
+}
+
 impl<M: ReplicaCommon> Replica<M::PN, M::DN, M::CW, M::S, M::A, M> {
     fn insert_view_change(
         &mut self,
         view_change: Verifiable<ViewChange>,
         timer: &mut impl Timer<Self>,
     ) -> anyhow::Result<()> {
-        if view_change.view_num < self.view_num
-            || view_change.view_num == self.view_num && !self.view_change()
-        {
+        if self.have_entered(view_change.view_num) {
             return Ok(());
         }
         let view_change_quorum = self.view_changes.entry(view_change.view_num).or_default();
@@ -1293,10 +1274,7 @@ impl<M: ReplicaCommon> OnEvent<Signed<NewView>> for Replica<M::PN, M::DN, M::CW,
         &mut self,
         Signed(new_view): Signed<NewView>,
         timer: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
+    ) -> anyhow::Result<()> {
         if self.view_num == new_view.view_num {
             self.net.send(All, new_view.clone())?;
             self.enter_view(new_view, timer)?
@@ -1311,7 +1289,7 @@ impl<M: ReplicaCommon> Replica<M::PN, M::DN, M::CW, M::S, M::A, M> {
         new_view: Verifiable<NewView>,
         timer: &mut impl Timer<Self>,
     ) -> anyhow::Result<()> {
-        assert!(new_view.view_num >= self.view_num);
+        assert!(!self.have_entered(new_view.view_num));
         self.view_num = new_view.view_num;
         assert!(self.view_change());
         for pre_prepare in &new_view.pre_prepares {
@@ -1379,13 +1357,8 @@ impl<M: ReplicaCommon> OnEvent<Recv<Verifiable<NewView>>>
         &mut self,
         Recv(new_view): Recv<Verifiable<NewView>>,
         _: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
-        if self.view_num > new_view.view_num
-            || self.view_num == new_view.view_num && !self.view_change()
-        {
+    ) -> anyhow::Result<()> {
+        if self.have_entered(new_view.view_num) {
             return Ok(());
         }
         let num_replica = self.num_replica;
@@ -1413,10 +1386,9 @@ impl<M: ReplicaCommon> OnEvent<Recv<Verifiable<NewView>>>
                 anyhow::Ok(())
             };
             if do_verify().is_ok() {
-                sender.send(Verified(new_view))
-            } else {
-                Ok(())
+                sender.send(Verified(new_view))?
             }
+            Ok(())
         }))
     }
 }
@@ -1426,16 +1398,11 @@ impl<M: ReplicaCommon> OnEvent<Verified<NewView>> for Replica<M::PN, M::DN, M::C
         &mut self,
         Verified(new_view): Verified<NewView>,
         timer: &mut impl Timer<Self>,
-    ) -> anyhow::Result<()>
-    where
-        Self: Sized,
-    {
-        if self.view_num > new_view.view_num
-            || self.view_num == new_view.view_num && !self.view_change()
-        {
-            return Ok(());
+    ) -> anyhow::Result<()> {
+        if !self.have_entered(new_view.view_num) {
+            self.enter_view(new_view, timer)?
         }
-        self.enter_view(new_view, timer)
+        Ok(())
     }
 }
 
@@ -1504,7 +1471,7 @@ pub fn to_replica_on_buf<A: Addr>(
     buf: &[u8],
     sender: &mut impl SendReplicaRecvEvent<A>,
 ) -> anyhow::Result<()> {
-    deserialize::<ToReplica<A>>(buf)?.send(sender)
+    deserialize::<ToReplica<_>>(buf)?.send(sender)
 }
 
 #[cfg(test)]