diff --git a/crates/caldav/src/calendar_object/methods.rs b/crates/caldav/src/calendar_object/methods.rs
index 2d7fc3f..3044aa7 100644
--- a/crates/caldav/src/calendar_object/methods.rs
+++ b/crates/caldav/src/calendar_object/methods.rs
@@ -11,7 +11,7 @@ use rustical_ical::CalendarObject;
 use rustical_store::CalendarStore;
 use rustical_store::auth::Principal;
 use std::str::FromStr;
-use tracing::{debug, instrument};
+use tracing::{instrument, warn};
 
 #[instrument(skip(cal_store))]
 pub async fn get_event<C: CalendarStore>(
@@ -94,9 +94,13 @@ pub async fn put_event<C: CalendarStore>(
         true
     };
 
-    let Ok(object) = CalendarObject::from_ics(body.clone()) else {
-        debug!("invalid calendar data:\n{body}");
-        return Err(Error::PreconditionFailed(Precondition::ValidCalendarData));
+    let object = match CalendarObject::from_ics(body.clone()) {
+        Ok(object) => object,
+        Err(err) => {
+            warn!("invalid calendar data:\n{body}");
+            warn!("{err:#?}");
+            return Err(Error::PreconditionFailed(Precondition::ValidCalendarData));
+        }
     };
     let etag = object.get_etag();
     cal_store
diff --git a/crates/caldav/src/error.rs b/crates/caldav/src/error.rs
index 51e3da5..3fc5530 100644
--- a/crates/caldav/src/error.rs
+++ b/crates/caldav/src/error.rs
@@ -79,6 +79,9 @@ impl Error {
 
 impl IntoResponse for Error {
     fn into_response(self) -> axum::response::Response {
+        if let Self::PreconditionFailed(precondition) = self {
+            return precondition.into_response();
+        }
         if matches!(
             self.status_code(),
             StatusCode::INTERNAL_SERVER_ERROR | StatusCode::PRECONDITION_FAILED
diff --git a/src/integration_tests/caldav/calendar.rs b/src/integration_tests/caldav/calendar.rs
index 475fe1d..ae3e005 100644
--- a/src/integration_tests/caldav/calendar.rs
+++ b/src/integration_tests/caldav/calendar.rs
@@ -8,7 +8,7 @@ use rustical_store::{CalendarMetadata, CalendarStore};
 use rustical_store_sqlite::tests::{TestStoreContext, test_store_context};
 use tower::ServiceExt;
 
-fn mkcalendar_template(
+pub fn mkcalendar_template(
     CalendarMetadata {
         displayname,
         order: _order,
diff --git a/src/integration_tests/caldav/calendar_put.rs b/src/integration_tests/caldav/calendar_put.rs
new file mode 100644
index 0000000..b99f274
--- /dev/null
+++ b/src/integration_tests/caldav/calendar_put.rs
@@ -0,0 +1,77 @@
+use axum::body::Body;
+use headers::{Authorization, HeaderMapExt};
+use http::{Request, StatusCode};
+use rstest::rstest;
+use rustical_store::CalendarMetadata;
+use rustical_store_sqlite::tests::{TestStoreContext, test_store_context};
+use tower::ServiceExt;
+
+use crate::integration_tests::{
+    ResponseExtractString, caldav::calendar::mkcalendar_template, get_app,
+};
+
+#[rstest]
+#[tokio::test]
+async fn test_put_invalid(
+    #[from(test_store_context)]
+    #[future]
+    context: TestStoreContext,
+) {
+    let context = context.await;
+    let app = get_app(context.clone());
+
+    let calendar_meta = CalendarMetadata {
+        displayname: Some("Calendar".to_string()),
+        description: Some("Description".to_string()),
+        color: Some("#00FF00".to_string()),
+        order: 0,
+    };
+    let (principal, cal_id) = ("user", "calendar");
+    let url = format!("/caldav/principal/{principal}/{cal_id}");
+
+    let mut request = Request::builder()
+        .method("MKCALENDAR")
+        .uri(&url)
+        .body(Body::from(mkcalendar_template(&calendar_meta)))
+        .unwrap();
+    request
+        .headers_mut()
+        .typed_insert(Authorization::basic("user", "pass"));
+    let response = app.clone().oneshot(request).await.unwrap();
+    assert_eq!(response.status(), StatusCode::CREATED);
+
+    // Invalid calendar data
+    let ical = r"BEGIN:VCALENDAR
+VERSION:2.0
+PRODID:-//Example Corp.//CalDAV Client//EN
+BEGIN:VEVENT
+UID:20010712T182145Z-123401@example.com
+DTSTAMP:20060712T182145Z
+DTSTART:20060714T170000Z
+RRULE:UNTIL=123
+DTEND:20060715T040000Z
+SUMMARY:Bastille Day Party
+END:VEVENT
+END:VCALENDAR";
+
+    let mut request = Request::builder()
+        .method("PUT")
+        .uri(format!("{url}/qwue23489.ics"))
+        .header("If-None-Match", "*")
+        .header("Content-Type", "text/calendar")
+        .body(Body::from(ical))
+        .unwrap();
+    request
+        .headers_mut()
+        .typed_insert(Authorization::basic("user", "pass"));
+
+    let response = app.clone().oneshot(request).await.unwrap();
+    assert_eq!(response.status(), StatusCode::PRECONDITION_FAILED);
+    let body = response.extract_string().await;
+    insta::assert_snapshot!(body, @r#"
+    <?xml version="1.0" encoding="utf-8"?>
+    <error xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav" xmlns:CARD="urn:ietf:params:xml:ns:carddav" xmlns:CS="http://calendarserver.org/ns/" xmlns:PUSH="https://bitfire.at/webdav-push">
+        <CAL:valid-calendar-data/>
+    </error>
+    "#);
+}
diff --git a/src/integration_tests/caldav/mod.rs b/src/integration_tests/caldav/mod.rs
index 4a91cd7..5d7d532 100644
--- a/src/integration_tests/caldav/mod.rs
+++ b/src/integration_tests/caldav/mod.rs
@@ -9,6 +9,7 @@ use tower::ServiceExt;
 
 mod calendar;
 mod calendar_import;
+mod calendar_put;
 mod calendar_report;
 
 #[rstest]