diff --git a/CHANGELOG.md b/CHANGELOG.md
index 04cf38ea..1968dd9b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,7 +16,9 @@ If you are upgrading from v0.16.x, replace the binary (or run `docker pull`). If
   - Invalidate caches when group memberships change on an external directory.
   - Return OIDC errors instead of "failed to decode token".
   - User impersonation.
-- Task queue pagination by anchor.
+- Tasks:
+  - Delete locked tasks.
+  - Queue pagination by anchor.
 - Log viewer: All events show as `INFO`.
 - Registry: Allow changing object variants.
 - Node id renewal.
diff --git a/crates/jmap/src/registry/mapping/task.rs b/crates/jmap/src/registry/mapping/task.rs
index 12fad496..0d0b97c3 100644
--- a/crates/jmap/src/registry/mapping/task.rs
+++ b/crates/jmap/src/registry/mapping/task.rs
@@ -259,15 +259,6 @@ pub(crate) async fn task_set(
             continue;
         }
 
-        if !set.server.try_lock_task(task_id).await {
-            set.response.not_destroyed.append(
-                id,
-                SetError::forbidden().with_description(
-                    "Task is currently being processed and cannot be destroyed".to_string(),
-                ),
-            );
-            continue;
-        }
         locked_tasks.push(task_id);
 
         let due = task.due_timestamp();
diff --git a/crates/services/src/task_manager/lock.rs b/crates/services/src/task_manager/lock.rs
index 33b9984f..cb11a2e6 100644
--- a/crates/services/src/task_manager/lock.rs
+++ b/crates/services/src/task_manager/lock.rs
@@ -24,7 +24,6 @@ impl TaskLockManager for Server {
                         TaskManager(TaskManagerEvent::TaskLocked),
                         Id = id,
                         Details = "Task details not available",
-                        Expires = trc::Value::Timestamp(now() + DEFAULT_LOCK_EXPIRY),
                     );
                 }
                 result
diff --git a/crates/services/src/task_manager/manager.rs b/crates/services/src/task_manager/manager.rs
index b8f89317..c76a61c9 100644
--- a/crates/services/src/task_manager/manager.rs
+++ b/crates/services/src/task_manager/manager.rs
@@ -40,7 +40,7 @@ use store::rand::seq::SliceRandom;
 use store::write::key::DeserializeBigEndian;
 use store::{
     IterateParams, ValueKey,
-    write::{BatchBuilder, TaskQueueClass, ValueClass, now},
+    write::{BatchBuilder, TaskQueueClass, ValueClass, assert::AssertValue, now},
 };
 use store::{SerializeInfallible, U64_LEN, rand};
 use tokio::sync::{mpsc, watch};
@@ -574,6 +574,10 @@ async fn update_tasks(
                     u64::MAX
                 };
                 batch
+                    .assert_value(
+                        ValueClass::TaskQueue(TaskQueueClass::Task { id }),
+                        AssertValue::Some,
+                    )
                     .set(
                         ValueClass::TaskQueue(TaskQueueClass::Due { id, due }),
                         task.info.typ.to_id().serialize(),
@@ -587,7 +591,14 @@ async fn update_tasks(
     }
 
     if let Err(err) = server.store().write(batch.build_all()).await {
-        trc::error!(err.details("Failed to remove task(s) from queue."));
+        if err.matches(trc::EventType::Store(trc::StoreEvent::AssertValueFailed)) {
+            trc::event!(
+                TaskManager(TaskManagerEvent::TaskIgnored),
+                Reason = "Task was deleted while being processed; skipping update.",
+            );
+        } else {
+            trc::error!(err.details("Failed to remove task(s) from queue."));
+        }
     }
 
     for task in tasks {