diff --git a/linera-core/src/client/chain_state.rs b/linera-core/src/client/chain_state.rs
index 373d17c3043..7fa8863a2f2 100644
--- a/linera-core/src/client/chain_state.rs
+++ b/linera-core/src/client/chain_state.rs
@@ -44,9 +44,9 @@ pub struct ChainState {
     /// been processed by (i.e. been proposed to) our own local chain manager yet.
     pending_blobs: BTreeMap<BlobId, Blob>,
 
-    /// A mutex that is held whilst we are preparing the next block, to ensure that no
-    /// other client can begin preparing a block.
-    preparing_block: Arc<Mutex<()>>,
+    /// A mutex that is held whilst we are performing operations that should not be
+    /// attempted by multiple clients at the same time.
+    client_mutex: Arc<Mutex<()>>,
 }
 
 impl ChainState {
@@ -72,7 +72,7 @@ impl ChainState {
             pending_block: None,
             pending_blobs,
             received_certificate_trackers: HashMap::new(),
-            preparing_block: Arc::default(),
+            client_mutex: Arc::default(),
         };
         if let Some(block) = pending_block {
             state.set_pending_block(block);
@@ -161,7 +161,7 @@ impl ChainState {
         self.pending_blobs.clear();
     }
 
-    pub fn preparing_block(&self) -> Arc<Mutex<()>> {
-        self.preparing_block.clone()
+    pub fn client_mutex(&self) -> Arc<Mutex<()>> {
+        self.client_mutex.clone()
     }
 }
diff --git a/linera-core/src/client/mod.rs b/linera-core/src/client/mod.rs
index 51d2db3a117..f35823e61fa 100644
--- a/linera-core/src/client/mod.rs
+++ b/linera-core/src/client/mod.rs
@@ -871,6 +871,9 @@ where
         #[cfg(with_metrics)]
         let _latency = metrics::PREPARE_CHAIN_LATENCY.measure_latency();
 
+        let mutex = self.state().client_mutex();
+        let _guard = mutex.lock_owned().await;
+
         // Verify that our local storage contains enough history compared to the
         // expected block height. Otherwise, download the missing history from the
         // network.
@@ -1845,8 +1848,8 @@ where
         #[cfg(with_metrics)]
         let _latency = metrics::EXECUTE_BLOCK_LATENCY.measure_latency();
 
-        let block_mutex = self.state().preparing_block();
-        let _block_guard = block_mutex.lock_owned().await;
+        let mutex = self.state().client_mutex();
+        let _guard = mutex.lock_owned().await;
         match self.process_pending_block_without_prepare().await? {
             ClientOutcome::Committed(Some(certificate)) => {
                 return Ok(ExecuteBlockOutcome::Conflict(certificate))
@@ -3001,10 +3004,13 @@ where
     /// This is similar to `find_received_certificates` but for only one validator.
     /// We also don't try to synchronize the admin chain.
     #[tracing::instrument(level = "trace")]
-    pub async fn find_received_certificates_from_validator(
+    async fn find_received_certificates_from_validator(
         &self,
         remote_node: RemoteNode<P::Node>,
     ) -> Result<(), ChainClientError> {
+        let mutex = self.state().client_mutex();
+        let _guard = mutex.lock_owned().await;
+
         let chain_id = self.chain_id;
         // Proceed to downloading received certificates.
         let (name, tracker, certificates) = self