diff --git a/src/cache.rs b/src/cache.rs
index fc2ef4a..966462a 100644
--- a/src/cache.rs
+++ b/src/cache.rs
@@ -143,8 +143,8 @@ impl Cache {
                 None => return Err("should not happen, we've just tested keys are the same".into()),
             };
 
-            let items_l = cal_l.get_items().await;
-            let items_r = cal_r.get_items().await;
+            let items_l = cal_l.get_items().await?;
+            let items_r = cal_r.get_items().await?;
 
                     if keys_are_the_same(&items_l, &items_r) == false {
                 log::debug!("Different keys for items");
diff --git a/src/calendar/cached_calendar.rs b/src/calendar/cached_calendar.rs
index 3a7fd54..22d9e63 100644
--- a/src/calendar/cached_calendar.rs
+++ b/src/calendar/cached_calendar.rs
@@ -34,11 +34,11 @@ impl CachedCalendar {
     }
 
     /// Returns the list of tasks that this calendar contains
-    pub async fn get_tasks(&self) -> HashMap<ItemId, &Item> {
+    pub async fn get_tasks(&self) -> Result<HashMap<ItemId, &Item>, Box<dyn Error>> {
         self.get_tasks_modified_since(None).await
     }
     /// Returns the tasks that have been last-modified after `since`
-    pub async fn get_tasks_modified_since(&self, since: Option<DateTime<Utc>>) -> HashMap<ItemId, &Item> {
+    pub async fn get_tasks_modified_since(&self, since: Option<DateTime<Utc>>) -> Result<HashMap<ItemId, &Item>, Box<dyn Error>> {
         self.get_items_modified_since(since, Some(SearchFilter::Tasks)).await
     }
 }
@@ -69,7 +69,7 @@ impl PartialCalendar for CachedCalendar {
         Ok(())
     }
 
-    async fn get_items_modified_since(&self, since: Option<DateTime<Utc>>, filter: Option<SearchFilter>) -> HashMap<ItemId, &Item> {
+    async fn get_items_modified_since(&self, since: Option<DateTime<Utc>>, filter: Option<SearchFilter>) -> Result<HashMap<ItemId, &Item>, Box<dyn Error>> {
         let filter = filter.unwrap_or_default();
 
         let mut map = HashMap::new();
@@ -94,7 +94,7 @@ impl PartialCalendar for CachedCalendar {
             map.insert(item.id().clone(), item);
         }
 
-        map
+        Ok(map)
     }
 
     async fn get_item_ids(&mut self) -> HashSet<ItemId> {
@@ -109,14 +109,14 @@ impl PartialCalendar for CachedCalendar {
 #[async_trait]
 impl CompleteCalendar for CachedCalendar {
     /// Returns the items that have been deleted after `since`
-    async fn get_items_deleted_since(&self, since: DateTime<Utc>) -> HashSet<ItemId> {
-        self.deleted_items.range(since..)
+    async fn get_items_deleted_since(&self, since: DateTime<Utc>) -> Result<HashSet<ItemId>, Box<dyn Error>> {
+        Ok(self.deleted_items.range(since..)
             .map(|(_key, id)| id.clone())
-            .collect()
+            .collect())
     }
 
     /// Returns the list of items that this calendar contains
-    async fn get_items(&self) -> HashMap<ItemId, &Item> {
+    async fn get_items(&self) -> Result<HashMap<ItemId, &Item>, Box<dyn Error>> {
         self.get_items_modified_since(None, None).await
     }
 
diff --git a/src/provider.rs b/src/provider.rs
index bcedd1d..43402e0 100644
--- a/src/provider.rs
+++ b/src/provider.rs
@@ -80,7 +80,7 @@ where
             // Step 1 - "Server always wins", so a delteion from the server must be applied locally, even if it was locally modified.
             let mut local_dels = match last_sync {
                 None => HashSet::new(),
-                Some(date) => cal_local.get_items_deleted_since(date).await,
+                Some(date) => cal_local.get_items_deleted_since(date).await?,
             };
             if last_sync.is_some() {
                 let server_deletions = cal_server.find_deletions_from(cal_local.get_item_ids().await).await;
@@ -97,8 +97,8 @@ where
             }
 
             // Step 2 - Compare both changesets...
-            let server_mods = cal_server.get_items_modified_since(last_sync, None).await;
-            let mut local_mods = cal_local.get_items_modified_since(last_sync, None).await;
+            let server_mods = cal_server.get_items_modified_since(last_sync, None).await?;
+            let mut local_mods = cal_local.get_items_modified_since(last_sync, None).await?;
 
             // ...import remote changes,...
             let mut conflicting_tasks = Vec::new();
diff --git a/src/traits.rs b/src/traits.rs
index 9c5c9d6..cfde874 100644
--- a/src/traits.rs
+++ b/src/traits.rs
@@ -42,7 +42,7 @@ pub trait PartialCalendar {
 
     /// Returns the items that have been last-modified after `since`
     async fn get_items_modified_since(&self, since: Option<DateTime<Utc>>, filter: Option<crate::calendar::SearchFilter>)
-        -> HashMap<ItemId, &Item>;
+        -> Result<HashMap<ItemId, &Item>, Box<dyn Error>>;
 
     /// Get the IDs of all current items in this calendar
     async fn get_item_ids(&mut self) -> HashSet<ItemId>;
@@ -82,9 +82,9 @@ pub trait CompleteCalendar : PartialCalendar {
     /// Returns the items that have been deleted after `since`
     ///
     /// See also [`PartialCalendar::get_items_deleted_since`]
-    async fn get_items_deleted_since(&self, since: DateTime<Utc>) -> HashSet<ItemId>;
+    async fn get_items_deleted_since(&self, since: DateTime<Utc>) -> Result<HashSet<ItemId>, Box<dyn Error>>;
 
     /// Returns the list of items that this calendar contains
-    async fn get_items(&self) -> HashMap<ItemId, &Item>;
+    async fn get_items(&self) -> Result<HashMap<ItemId, &Item>, Box<dyn Error>>;
 }
 
diff --git a/src/utils.rs b/src/utils.rs
index d0b398d..cfcbe5f 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -64,8 +64,13 @@ where
 {
     for (id, cal) in cals {
         println!("CAL {}", id);
-        for (_, item) in cal.lock().unwrap().get_items().await {
-            print_task(item);
+        match cal.lock().unwrap().get_items().await {
+            Err(_err) => continue,
+            Ok(map) => {
+                for (_, item) in map {
+                    print_task(item);
+                }
+            },
         }
     }
 }
diff --git a/tests/caldav_client.rs b/tests/caldav_client.rs
index df6cdf6..b03b600 100644
--- a/tests/caldav_client.rs
+++ b/tests/caldav_client.rs
@@ -48,7 +48,7 @@ async fn show_calendars() {
         let cal = calendar.lock().unwrap();
         println!("  {}\t{}", cal.name(), id.as_str());
         println!("  Most recent changes:");
-        for (_id, task) in cal.get_items_modified_since(None, None).await {
+        for (_id, task) in cal.get_items_modified_since(None, None).await.unwrap() {
             my_tasks::utils::print_task(task);
         }
     }