diff --git a/backend/src/appointment/controller/calendar.py b/backend/src/appointment/controller/calendar.py
index fccf00618..5f428c951 100644
--- a/backend/src/appointment/controller/calendar.py
+++ b/backend/src/appointment/controller/calendar.py
@@ -33,6 +33,7 @@
 from ..database.models import CalendarProvider, BookingStatus
 from ..database import schemas, models, repo
 from ..controller.mailer import Attachment
+from ..exceptions.calendar import TestConnectionFailed
 from ..exceptions.validation import RemoteCalendarConnectionError
 from ..l10n import l10n
 from ..tasks.emails import send_invite_email, send_pending_email, send_rejection_email
@@ -329,24 +330,36 @@ def test_connection(self) -> bool:
         except IndexError as ex:
             # Library has an issue with top level urls, probably due to caldav spec?
             logging.error(f'IE: Error testing connection {ex}')
-            return False
+            raise TestConnectionFailed(reason=None)
         except KeyError as ex:
             logging.error(f'KE: Error testing connection {ex}')
-            return False
+            raise TestConnectionFailed(reason=None)
+        except requests.exceptions.RequestException:
+            raise TestConnectionFailed(reason=None)
+        except NotImplementedError:
+            # Doesn't support authorization by digest, bearer, or basic header values
+            raise TestConnectionFailed(reason=l10n('remote-calendar-reason-doesnt-support-auth'))
         except (
-            requests.exceptions.RequestException,
             caldav.lib.error.NotFoundError,
             caldav.lib.error.PropfindError,
             caldav.lib.error.AuthorizationError
         ) as ex:
             """
-            RequestException: Max retries exceeded, bad connection, missing schema, etc...
             NotFoundError: Good server, bad url.
             PropfindError: Some properties could not be retrieved.
             AuthorizationError: Credentials are not accepted.
             """
             logging.error(f'Test Connection Error: {ex}')
-            return False
+
+            # Don't use the default "no reason" error message if we encounter it.
+            if ex.reason == caldav.lib.error.DAVError.reason:
+                ex.reason = None
+            if ex.reason == 'Unauthorized':
+                # ex.reason seems to be pulling from status codes for some errors?
+                # Let's replace this with our own.
+                ex.reason = l10n('remote-calendar-reason-unauthorized')
+
+            raise TestConnectionFailed(reason=ex.reason)
 
         # They need at least VEVENT support for appointment to work.
         return supports_vevent
diff --git a/backend/src/appointment/exceptions/calendar.py b/backend/src/appointment/exceptions/calendar.py
index f5a1b9899..03e749f6d 100644
--- a/backend/src/appointment/exceptions/calendar.py
+++ b/backend/src/appointment/exceptions/calendar.py
@@ -1,8 +1,17 @@
 class EventNotCreatedException(Exception):
     """Raise if an event cannot be created on a remote calendar"""
+
     pass
 
 
 class EventNotDeletedException(Exception):
     """Raise if an event cannot be deleted on a remote calendar"""
+
     pass
+
+
+class TestConnectionFailed(Exception):
+    """Raise if test connection fails, include remote error message."""
+
+    def __init__(self, reason: str | None = None):
+        self.reason = reason
diff --git a/backend/src/appointment/exceptions/validation.py b/backend/src/appointment/exceptions/validation.py
index b01689ffa..394adefe4 100644
--- a/backend/src/appointment/exceptions/validation.py
+++ b/backend/src/appointment/exceptions/validation.py
@@ -205,9 +205,19 @@ def get_msg(self):
 class RemoteCalendarConnectionError(APIException):
     id_code = 'REMOTE_CALENDAR_CONNECTION_ERROR'
     status_code = 400
+    reason = None
+
+    def __init__(self, reason: str|None, **kwargs):
+        if reason:
+            self.reason = reason
+        super().__init__(**kwargs)
 
     def get_msg(self):
-        return l10n('remote-calendar-connection-error')
+        reason = self.reason
+        if not self.reason:
+            reason = l10n('unknown-error-short')
+
+        return l10n('remote-calendar-connection-error', {'reason': reason})
 
 
 class EventCouldNotBeAccepted(APIException):
diff --git a/backend/src/appointment/l10n/de/main.ftl b/backend/src/appointment/l10n/de/main.ftl
index 1b26cccdf..f97d10eac 100644
--- a/backend/src/appointment/l10n/de/main.ftl
+++ b/backend/src/appointment/l10n/de/main.ftl
@@ -19,6 +19,7 @@ health-bad = Zustand schlecht
 ## General Exceptions
 
 unknown-error = Ein unbekannter Fehler ist aufgetreten. Bitte später noch einmal versuchen.
+unknown-error-short = Unbekannter Fehler
 
 appointment-not-found = Der Termin konnte nicht gefunden werden.
 calendar-not-found = Der Kalender konnte nicht gefunden werden.
@@ -45,7 +46,15 @@ not-in-allow-list = Deine E-Mail-Adresse ist nicht in der Liste erlaubter Adress
 
 schedule-not-active = Der Zeitplan wurde abgeschaltet. Bitte für weitere Informationen den Eigentümer des Zeitplans kontaktieren.
 
-remote-calendar-connection-error = Der angebundene Kalender konnte nicht erreicht werden. Bitte die Verbindungsinformationen überprüfen und noch einmal versuchen.
+remote-calendar-connection-error = Der angebundene Kalender konnte nicht erreicht werden: {$reason}.
+remote-calendar-connection-error = The remote calendar could not be reached due to {$reason}.
+
+        Bitte die Verbindungsinformationen überprüfen und noch einmal versuchen.
+
+# Possible entries for $reason,
+remote-calendar-reason-doesnt-support-caldav = Der Kalender bietet keine CalDAV-Unterstützung
+remote-calendar-reason-doesnt-support-auth = Der Kalender unterstützt keine Authentifizierung
+remote-calendar-reason-unauthorized = Es gibt ein Problem mit Benutzername oder Passwort
 
 event-could-not-be-accepted = Es ist ein Fehler bei der Annahme der Buchungsdaten aufgetreten. Bitte später noch einmal versuchen.
 event-could-not-be-deleted = Es ist ein Fehler beim Entfernen des vorläufigen Termins aufgetreten. Bitte später noch einmal versuchen.
diff --git a/backend/src/appointment/l10n/en/main.ftl b/backend/src/appointment/l10n/en/main.ftl
index 541fb8d6b..fb5b54c14 100644
--- a/backend/src/appointment/l10n/en/main.ftl
+++ b/backend/src/appointment/l10n/en/main.ftl
@@ -19,6 +19,7 @@ health-bad = Health BAD
 ## General Exceptions
 
 unknown-error = An unknown error occurred. Please try again later.
+unknown-error-short = an unknown error
 
 appointment-not-found = The appointment could not be found.
 calendar-not-found = The calendar could not be found.
@@ -45,7 +46,14 @@ not-in-allow-list = Your email is not in the allow list.
 
 schedule-not-active = The schedule has been turned off. Please contact the schedule owner for more information.
 
-remote-calendar-connection-error = The remote calendar could not be reached. Please verify your connection information and try again.
+remote-calendar-connection-error = The remote calendar could not be reached due to {$reason}.
+
+        Please verify your connection information and try again.
+
+# Possible entries for $reason,
+remote-calendar-reason-doesnt-support-caldav = the remote calendar does not support CalDAV
+remote-calendar-reason-doesnt-support-auth = the remote calendar does not support authentication
+remote-calendar-reason-unauthorized = an issue with your username or password
 
 event-could-not-be-accepted = There was an error accepting the booking details. Please try again later.
 event-could-not-be-deleted = There was an error removing the hold event. Please try again later.
diff --git a/backend/src/appointment/routes/caldav.py b/backend/src/appointment/routes/caldav.py
index 41e98088f..221b49891 100644
--- a/backend/src/appointment/routes/caldav.py
+++ b/backend/src/appointment/routes/caldav.py
@@ -12,8 +12,10 @@
 from appointment.database import models, schemas, repo
 from appointment.dependencies.auth import get_subscriber
 from appointment.dependencies.database import get_db, get_redis
+from appointment.exceptions.calendar import TestConnectionFailed
 from appointment.exceptions.misc import UnexpectedBehaviourWarning
 from appointment.exceptions.validation import RemoteCalendarConnectionError
+from appointment.l10n import l10n
 
 router = APIRouter()
 
@@ -99,8 +101,13 @@ def caldav_autodiscover_auth(
         calendar_id=None,
     )
 
-    if not con.test_connection():
-        raise RemoteCalendarConnectionError()
+    # If it returns False it doesn't support VEVENT (aka caldav)
+    # If it raises an exception there's a connection problem
+    try:
+        if not con.test_connection():
+            raise RemoteCalendarConnectionError(reason=l10n('remote-calendar-reason-doesnt-support-caldav'))
+    except TestConnectionFailed as ex:
+        raise RemoteCalendarConnectionError(reason=ex.reason)
 
     caldav_id = json.dumps([connection.url, connection.user])
     external_connection = repo.external_connection.get_by_type(
diff --git a/frontend/src/tbpro/elements/NoticeBar.vue b/frontend/src/tbpro/elements/NoticeBar.vue
index 99e5de0a0..b7ccd7932 100644
--- a/frontend/src/tbpro/elements/NoticeBar.vue
+++ b/frontend/src/tbpro/elements/NoticeBar.vue
@@ -51,6 +51,7 @@ const isError = props.type === 'error';
   font-size: 0.8125rem;
   font-weight: 700;
   line-height: 1;
+  white-space: pre;
 }
 .notice {
   position: relative;