diff --git a/crates/matrix-sdk/src/send_queue.rs b/crates/matrix-sdk/src/send_queue.rs
index 0b96416d049..a842a9e895e 100644
--- a/crates/matrix-sdk/src/send_queue.rs
+++ b/crates/matrix-sdk/src/send_queue.rs
@@ -146,6 +146,7 @@ use matrix_sdk_base::{
         FinishUploadThumbnailInfo, QueueWedgeError, QueuedRequest, QueuedRequestKind,
         SentMediaInfo, SentRequestKey, SerializableEventContent,
     },
+    store_locks::LockStoreError,
     RoomState, StoreError,
 };
 use matrix_sdk_common::executor::{spawn, JoinHandle};
@@ -693,10 +694,16 @@ impl RoomSendQueue {
                     })
                 })?;
 
-                let data =
-                    room.client().event_cache_store().get_media_content(&cache_key).await?.ok_or(
-                        crate::Error::SendQueueWedgeError(QueueWedgeError::MissingMediaContent),
-                    )?;
+                let data = room
+                    .client()
+                    .event_cache_store()
+                    .lock()
+                    .await?
+                    .get_media_content(&cache_key)
+                    .await?
+                    .ok_or(crate::Error::SendQueueWedgeError(
+                        QueueWedgeError::MissingMediaContent,
+                    ))?;
 
                 #[cfg(feature = "e2e-encryption")]
                 let media_source = if room.is_encrypted().await? {
@@ -1676,6 +1683,10 @@ pub enum RoomSendQueueStorageError {
     #[error(transparent)]
     EventCacheStoreError(#[from] EventCacheStoreError),
 
+    /// Error caused when attempting to get a handle on the event cache store.
+    #[error(transparent)]
+    LockError(#[from] LockStoreError),
+
     /// Error caused when (de)serializing into/from json.
     #[error(transparent)]
     JsonSerialization(#[from] serde_json::Error),
diff --git a/crates/matrix-sdk/src/send_queue/upload.rs b/crates/matrix-sdk/src/send_queue/upload.rs
index e3142dda028..2c38977387c 100644
--- a/crates/matrix-sdk/src/send_queue/upload.rs
+++ b/crates/matrix-sdk/src/send_queue/upload.rs
@@ -160,60 +160,66 @@ impl RoomSendQueue {
         Span::current().record("event_txn", tracing::field::display(&*send_event_txn));
         debug!(filename, %content_type, %upload_file_txn, "sending an attachment");
 
-        // Cache the file itself in the cache store.
         let file_media_request = make_local_file_media_request(&upload_file_txn);
-        room.client()
-            .event_cache_store()
-            .add_media_content(&file_media_request, data.clone())
-            .await
-            .map_err(|err| RoomSendQueueError::StorageError(err.into()))?;
 
-        // Process the thumbnail, if it's been provided.
-        let (upload_thumbnail_txn, event_thumbnail_info, queue_thumbnail_info) = if let Some(
-            thumbnail,
-        ) =
-            config.thumbnail.take()
-        {
-            // Normalize information to retrieve the thumbnail in the cache store.
-            let info = thumbnail.info.as_ref();
-            let height = info.and_then(|info| info.height).unwrap_or_else(|| {
-                trace!("thumbnail height is unknown, using 0 for the cache entry");
-                uint!(0)
-            });
-            let width = info.and_then(|info| info.width).unwrap_or_else(|| {
-                trace!("thumbnail width is unknown, using 0 for the cache entry");
-                uint!(0)
-            });
-
-            let txn = TransactionId::new();
-            trace!(upload_thumbnail_txn = %txn, thumbnail_size = ?(height, width), "attachment has a thumbnail");
-
-            // Cache thumbnail in the cache store.
-            let thumbnail_media_request = make_local_thumbnail_media_request(&txn, height, width);
-            room.client()
+        let (upload_thumbnail_txn, event_thumbnail_info, queue_thumbnail_info) = {
+            let client = room.client();
+            let cache_store = client
                 .event_cache_store()
-                .add_media_content(&thumbnail_media_request, thumbnail.data.clone())
+                .lock()
                 .await
-                .map_err(|err| RoomSendQueueError::StorageError(err.into()))?;
-
-            // Create the information required for filling the thumbnail section of the
-            // media event.
-            let thumbnail_info =
-                Box::new(assign!(thumbnail.info.map(ThumbnailInfo::from).unwrap_or_default(), {
-                    mimetype: Some(thumbnail.content_type.as_ref().to_owned())
-                }));
-
-            (
-                Some(txn.clone()),
-                Some((thumbnail_media_request.source.clone(), thumbnail_info)),
-                Some((
-                    FinishUploadThumbnailInfo { txn, width, height },
-                    thumbnail_media_request,
-                    thumbnail.content_type,
-                )),
-            )
-        } else {
-            Default::default()
+                .map_err(RoomSendQueueStorageError::LockError)?;
+
+            // Cache the file itself in the cache store.
+            cache_store
+                .add_media_content(&file_media_request, data.clone())
+                .await
+                .map_err(RoomSendQueueStorageError::EventCacheStoreError)?;
+
+            // Process the thumbnail, if it's been provided.
+            if let Some(thumbnail) = config.thumbnail.take() {
+                // Normalize information to retrieve the thumbnail in the cache store.
+                let info = thumbnail.info.as_ref();
+                let height = info.and_then(|info| info.height).unwrap_or_else(|| {
+                    trace!("thumbnail height is unknown, using 0 for the cache entry");
+                    uint!(0)
+                });
+                let width = info.and_then(|info| info.width).unwrap_or_else(|| {
+                    trace!("thumbnail width is unknown, using 0 for the cache entry");
+                    uint!(0)
+                });
+
+                let txn = TransactionId::new();
+                trace!(upload_thumbnail_txn = %txn, thumbnail_size = ?(height, width), "attachment has a thumbnail");
+
+                // Cache thumbnail in the cache store.
+                let thumbnail_media_request =
+                    make_local_thumbnail_media_request(&txn, height, width);
+                cache_store
+                    .add_media_content(&thumbnail_media_request, thumbnail.data.clone())
+                    .await
+                    .map_err(RoomSendQueueStorageError::EventCacheStoreError)?;
+
+                // Create the information required for filling the thumbnail section of the
+                // media event.
+                let thumbnail_info = Box::new(
+                    assign!(thumbnail.info.map(ThumbnailInfo::from).unwrap_or_default(), {
+                        mimetype: Some(thumbnail.content_type.as_ref().to_owned())
+                    }),
+                );
+
+                (
+                    Some(txn.clone()),
+                    Some((thumbnail_media_request.source.clone(), thumbnail_info)),
+                    Some((
+                        FinishUploadThumbnailInfo { txn, width, height },
+                        thumbnail_media_request,
+                        thumbnail.content_type,
+                    )),
+                )
+            } else {
+                Default::default()
+            }
         };
 
         // Create the content for the media event.
@@ -296,8 +302,13 @@ impl QueueStorage {
 
             trace!(from = ?from_req.source, to = ?sent_media.file, "renaming media file key in cache store");
 
-            client
+            let cache_store = client
                 .event_cache_store()
+                .lock()
+                .await
+                .map_err(RoomSendQueueStorageError::LockError)?;
+
+            cache_store
                 .replace_media_key(
                     &from_req,
                     &MediaRequestParameters {
@@ -320,8 +331,7 @@ impl QueueStorage {
                 // Reuse the same format for the cached thumbnail with the final MXC ID.
                 let new_format = from_req.format.clone();
 
-                client
-                    .event_cache_store()
+                cache_store
                     .replace_media_key(
                         &from_req,
                         &MediaRequestParameters { source: new_source, format: new_format },